Imaging lens, optical apparatus equipped therewith, and method for manufacturing imaging lens

ABSTRACT

An imaging lens including, in order from an object side: a first lens group G 1  having positive refractive power; and a second lens group G 2  having positive refractive power, a position of the first lens group G 1  being fixed with respect to an image plane, the second lens group G 2  consisting of a plurality of lens components, and given conditional expression being satisfied, thereby providing a compact imaging lens imaging lens having a large aperture and a wide angle of view and excellent optical performance over entire image frame with excellently correcting various aberrations upon focusing on an infinity object to a close object.

The disclosure of the following priority applications are hereinincorporated by reference:

-   Japanese Patent Application No. 2010-104444 filed on Apr. 28, 2010,-   Japanese Patent Application No. 2010-104450 filed on Apr. 28, 2010,-   Japanese Patent Application No. 2010-104461 filed on Apr. 28, 2010.-   Japanese Patent Application No. 2011-089196 filed on Apr. 13, 2011,-   Japanese Patent Application No. 2011-089204 filed on Apr. 13, 2011,    and-   Japanese Patent Application No. 2011-089211 filed on Apr. 13, 2011.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging lens, an optical apparatusequipped with the imaging lens, and a method for manufacturing theimaging lens.

2. Related Background Art

A compact imaging lens suitable for a photographic camera, a videocamera, and the like having an angle of view of about 50 degrees andrelatively small value of an f-number has been proposed. Moreover, insuch an imaging lens, there has been known a lens configurationincluding, in order from an object side, a first lens group composed ofa negative lens and a positive lens, an aperture stop, and a second lensgroup composed of a cemented lens constructed by a negative lenscemented with a positive lens, and a positive lens, for example,Japanese Patent Application Laid-Open No. 9-189856.

However, in such a conventional imaging lens, when the whole lens ismoved for focusing, the total lens length becomes long upon focusingfrom an infinity object to a close object. Moreover, various aberrationscannot be sufficiently corrected upon focusing on a close object.

Moreover, in a conventional camera equipped with such an imaging lens,when the camera becomes small, thin and lightweight, holding of thecamera becomes difficult resulting in increase in shooting error causeby a camera shake or the like. In other words, the image is deterioratedby an image blur during exposure caused by a minute camera shaketriggered by a hand movement occurred upon shooting (for example, acamera shake generated upon depressing a release button).

Accordingly, there has been known a method for correcting an image blurwith installing a driving system that shifts a portion of lens as ashift lens group in a direction perpendicular to an optical axis, adetection system that detects a camera shake, and a calculation systemthat controls the driving system on the basis of a detection result ofthe detection system into such a conventional imaging lens.

However, in the above-described imaging lens capable of correcting animage blur, there has been a problem that various aberrations cannot beexcellently corrected, and optical performance varies upon shifting theshifting lens group.

SUMMARY OF THE INVENTION

The present invention is made in view of the above-described problemsand has an object to provide a compact imaging lens having a largeaperture and a wide angle of view and excellent optical performance overentire image frame with excellently correcting various aberrations uponfocusing on an infinity object to a close object with suppressingvariation in optical performance upon shifting the shifting lens group,an optical apparatus equipped with the imaging lens, and a method formanufacturing the imaging lens. According to a first aspect of thepresent invention, there is provided an imaging lens comprising, inorder from an object side: a first lens group having positive refractivepower; and a second lens group having positive refractive power, aposition of the first lens group being fixed with respect to an imageplane, the second lens group consisting of a plurality of lenscomponents, and the following conditional expression (1) beingsatisfied:

0.015<f/f1<0.085  (1)

where f denotes a focal length of the imaging lens, and f1 denotes afocal length of the first lens group.

According to a second aspect of the present invention, there is providedan optical apparatus equipped with the imaging lens according to thefirst aspect.

According to a third aspect of the present invention, there is providedan imaging lens comprising, in order from an object side: a first lensgroup having positive refractive power; and a second lens group havingpositive refractive power, the first lens group consisting of a singlelens component, the second lens group consisting of, in order from theobject side, a front lens group, an aperture stop, and a rear lensgroup, and at least a portion of the second lens group being moved as ashift lens group in a direction including a component perpendicular toan optical axis.

According to a fourth aspect of the present invention, there is providedan optical apparatus equipped with the imaging lens according to thirdaspect.

According to a fifth aspect of the present invention, there is providedan imaging lens comprising, in order from an object side: a first lensgroup having positive refractive power; and a second lens group havingpositive refractive power, the first lens group consisting of a singlepositive lens component having convex surface facing an image side, thesecond lens group consisting of, in order from the object side, anegative meniscus lens having a convex surface facing the object side, apositive lens having a convex surface facing the object side, anaperture stop, a cemented lens constructed by a negative lens having aconcave surface facing the object side cemented with a positive lenshaving a convex surface facing the image side, and a positive lens, andat least a portion of the second lens group being moved along an opticalaxis, thereby carrying out focusing from an infinity object to a closeobject.

According to a sixth aspect of the present invention, there is providedan optical apparatus equipped with the imaging lens according to fifthaspect.

According to a seventh aspect of the present invention, there isprovided a method for manufacturing an imaging lens including, in orderfrom an object side, a first lens group having positive refractive powerand a second lens group having positive refractive power, the methodcomprising steps of: disposing the second lens group with consisting ofa plurality of lens components; disposing the imaging lens withsatisfying the following conditional expression (1):

0.015<f/f1<0.085  (1)

where f denotes a focal length of the imaging lens, and f1 denotes afocal length of the first lens group; and fixing a position of the firstlens group with respect to the image plane.

According to an eighth aspect of the present invention, there isprovided a method for manufacturing an imaging lens including, in orderfrom the object side, a first lens group having positive refractivepower and a second lens group having positive refractive power, themethod comprising steps of: disposing the first lens group with a singlelens component; disposing the second lens group consisting of, in orderfrom the object side, a front lens group, an aperture stop, and a rearlens group; and moving at least a portion of the second lens group as ashift lens group in a direction including a component perpendicular toan optical axis.

According to a ninth aspect of the present invention, there is provideda method for manufacturing an imaging lens including, in order from anobject side, a first lens group having positive refractive power and asecond lens group having positive refractive power, the methodcomprising steps of: disposing the first lens group with a singlepositive lens component having a convex surface facing an image side;disposing the second lens group consisting of, in order from the objectside, a negative meniscus lens having a convex surface facing the objectside, a positive lens having a convex surface facing the object side, anaperture stop, a cemented lens constructed by a negative lens having aconcave surface facing the object side cemented with a positive lenshaving a convex surface facing the image side, and a positive lens; andmoving at least a portion of the second lens group along an opticalaxis, thereby carrying out focusing from an infinity object to a closeobject.

The present invention makes it possible to provide a compact imaginglens having a large aperture and a wide angle of view and excellentoptical performance over entire image frame with excellently correctingvarious aberrations upon focusing on an infinity object to a closeobject with suppressing variation in optical performance upon shiftingthe shifting lens group, an optical apparatus equipped with the imaginglens, and a method for manufacturing the imaging lens.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view showing a lens configuration of an imaginglens according to Example 1 of a first embodiment of the presentapplication.

FIGS. 2A and 2B are graphs showing various aberrations of the imaginglens according to Example 1 of the first embodiment, in which FIG. 2A isupon focusing on an infinity object, and FIG. 2B is upon focusing on aclose shooting distance.

FIG. 3 is a sectional view showing a lens configuration of an imaginglens according to Example 2 of the first embodiment of the presentapplication.

FIGS. 4A and 4B are graphs showing various aberrations of the imaginglens according to Example 2 of the first embodiment, in which FIG. 4A isupon focusing on an infinity object, and FIG. 4B is upon focusing on aclose shooting distance.

FIG. 5 is a sectional view showing a lens configuration of an imaginglens according to Example 3 of the first embodiment of the presentapplication.

FIGS. 6A and 6B are graphs showing various aberrations of the imaginglens according to Example 3 of the first embodiment, in which FIG. 6A isupon focusing on an infinity object, and FIG. 6B is upon focusing on aclose shooting distance.

FIG. 7 is a sectional view showing a lens configuration of an imaginglens according to Example 4 of the first embodiment of the presentapplication.

FIGS. 8A and 8B are graphs showing various aberrations of the imaginglens according to Example 4 of the first embodiment, in which FIG. 8A isupon focusing on an infinity object, and FIG. 8B is upon focusing on aclose shooting distance.

FIG. 9 is a sectional view showing a lens configuration of an imaginglens according to Example 5 of the first embodiment of the presentapplication.

FIGS. 10A and 10B are graphs showing various aberrations of the imaginglens according to Example 5 of the first embodiment, in which FIG. 10Ais upon focusing on an infinity object, and FIG. 10B is upon focusing ona close shooting distance.

FIG. 11 is a sectional view showing a lens configuration of an imaginglens according to Example 6 of the first embodiment of the presentapplication.

FIGS. 12A and 12B are graphs showing various aberrations of the imaginglens according to Example 6 of the first embodiment, in which FIG. 12Ais upon focusing on an infinity object, and FIG. 12B is upon focusing ona close shooting distance.

FIG. 13 is a sectional view showing a lens configuration of an imaginglens according to Example 7 of the first embodiment of the presentapplication.

FIGS. 14A and 14B are graphs showing various aberrations of the imaginglens according to Example 7 of the first embodiment, in which FIG. 14Ais upon focusing on an infinity object, and FIG. 14B is upon focusing ona close shooting distance.

FIG. 15 is a sectional view showing a lens configuration of an imaginglens according to Example 8 of a second embodiment of the presentapplication.

FIGS. 16A, 16B and 16C are graphs showing various aberrations of theimaging lens according to Example 8 of the second embodiment, in whichFIG. 16A is upon focusing on an infinity object, FIG. 16B is uponfocusing on a close shooting distance, and FIG. 16C shows coma uponvibration reduction.

FIG. 17 is a sectional view showing a lens configuration of an imaginglens according to Example 9 of the second embodiment of the presentapplication.

FIGS. 18A, 18B and 18C are graphs showing various aberrations of theimaging lens according to Example 9 of the second embodiment, in whichFIG. 18A is upon focusing on an infinity object, FIG. 18B is uponfocusing on a close shooting distance, and FIG. 18C shows coma uponvibration reduction.

FIG. 19 is a sectional view showing a lens configuration of an imaginglens according to Example 10 of the second embodiment of the presentapplication.

FIGS. 20A, 20B and 20C are graphs showing various aberrations of theimaging lens according to Example 10 of the second embodiment, in whichFIG. 20A is upon focusing on an infinity object, FIG. 20B is uponfocusing on a close shooting distance, and FIG. 20C shows coma uponvibration reduction.

FIG. 21 is a sectional view showing a lens configuration of an imaginglens according to Example 11 of the second embodiment of the presentapplication.

FIGS. 22A, 22B and 22C are graphs showing various aberrations of theimaging lens according to Example 11 of the second embodiment, in whichFIG. 22A is upon focusing on an infinity object, FIG. 22B is uponfocusing on a close shooting distance, and FIG. 22C shows coma uponvibration reduction.

FIG. 23 is a sectional view showing a lens configuration of an imaginglens according to Example 12 of the second embodiment of the presentapplication.

FIGS. 24A, 24B and 24C are graphs showing various aberrations of theimaging lens according to Example 12 of the second embodiment, in whichFIG. 24A is upon focusing on an infinity object, FIG. 24B is uponfocusing on a close shooting distance, and FIG. 24C shows coma uponvibration reduction.

FIG. 25 is a sectional view showing a lens configuration of an imaginglens according to Example 13 of the second embodiment of the presentapplication.

FIGS. 26A, 26B and 26C are graphs showing various aberrations of theimaging lens according to Example 13 of the second embodiment, in whichFIG. 26A is upon focusing on an infinity object, FIG. 26B is uponfocusing on a close shooting distance, and FIG. 26C shows coma uponvibration reduction.

FIG. 27 is a sectional view showing a lens configuration of an imaginglens according to Example 14 of the second embodiment of the presentapplication.

FIGS. 28A, 28B and 28C are graphs showing various aberrations of theimaging lens according to Example 14 of the second embodiment, in whichFIG. 28A is upon focusing on an infinity object, FIG. 28B is uponfocusing on a close shooting distance, and FIG. 28C shows coma uponvibration reduction.

FIGS. 29A and 29B are diagrams showing an electronic camera according tothe present application, in which FIG. 29A is a front view and FIG. 29Bis a rear view

FIG. 30 is a sectional view along A-A′ line in FIG. 29A.

FIG. 31 is a flowchart showing a method for manufacturing an imaginglens according to the first embodiment of the present embodiment.

FIG. 32 is a flowchart showing a method for manufacturing an imaginglens seen from another point of view according to the first embodimentof the present application.

FIG. 33 is a flowchart showing a method for manufacturing an imaginglens according to the second embodiment of the present application.

DESCRIPTION OF THE MOST PREFERRED EMBODIMENT First Embodiment

An imaging lens, an optical apparatus equipped with the imaging lens anda method for manufacturing the imaging lens according to a firstembodiment of the present application are explained below.

An imaging lens according to the first embodiment of the presentapplication includes, in order from an object side, a first lens grouphaving positive refractive power and a second lens group having positiverefractive power. A position of the first lens group is fixed withrespect to an image plane. The second lens group is composed of aplurality of lens components. The following conditional expression (1)is satisfied:

0.015<f/f1<0.085  (1)

where f denotes a focal length of the imaging lens, and f1 denotes afocal length of the first lens group.

As described above, an imaging lens according to the first embodiment ofthe present application includes, in order from the object side, thefirst lens group having positive refractive power and the second lensgroup having positive refractive power, the position of the first lensgroup is fixed with respect to the image plane, and the second lensgroup is composed of a plurality of lens components. With this lensconfiguration, it becomes possible to realize a compact imaging lenshaving excellent optical performance. Incidentally, a lens component isdefined as a single lens or a cemented lens constructed by cementing twolenses or more.

In an imaging lens according to the first embodiment of the presentapplication, with satisfying conditional expression (1) under theconfiguration described above, spherical aberration and coma generatedin the first lens group alone can be suppressed minimally.

Conditional expression (1) defines the focal length of the first lensgroup and the focal length of the imaging lens.

When the ratio f/f1 is equal to or exceeds the upper limit ofconditional expression (1), spherical aberration and coma generated inthe first lens group alone become large, so that it becomes difficult tocorrect these aberrations. In order to secure the effect of the presentapplication, it is preferable to set the upper limit of conditionalexpression (1) to 0.080. In order to further secure the effect of thepresent application, it is most preferable to set the upper limit ofconditional expression (1) to 0.075.

On the other hand, when the ratio f/f1 is equal to or falls below thelower limit of conditional expression (1), the focal length of the firstlens group becomes large, and the total lens length of the imaging lensbecomes large, so that it becomes opposite to the intension of thepresent application. Moreover, when the total lens length of the imaginglens is to be secured, coma and curvature of field become worse, so thatit is undesirable. In order to secure the effect of the presentapplication, it is preferable to set the lower limit of conditionalexpression (1) to 0.020. In order to further secure the effect of thepresent application, it is most preferable to set the lower limit ofconditional expression (1) to 0.025.

With the configuration described above, it becomes possible to realize acompact imaging lens having a large aperture, a wide angle of view andexcellent optical performance over entire image frame with excellentlycorrecting various aberrations upon focusing on an infinity object to aclose object.

In an imaging lens according to the first embodiment of the presentapplication, the first lens group is preferably composed of a singlepositive lens component having a convex surface facing the object side.With this configuration, an imaging lens according to the presentapplication makes it possible to realize further excellent opticalperformance.

In an imaging lens according to the first embodiment of the presentapplication, the single positive lens component is preferably a singlelens. With this lens configuration, it becomes possible to excellentlycorrect distortion and curvature of field generated in the whole lenssystem of the imaging lens.

In an imaging lens according to the first embodiment of the presentapplication, at least a portion of the second lens group is preferablymoved to the object side, thereby carrying out focusing from an infinityobject to a close object. With this configuration, a moving amount ofthe focusing lens group toward the object side upon focusing becomesextremely small, so that variation in spherical aberration and curvatureof field can be excellently suppressed. Moreover, interference betweenlenses and mechanical parts that hold lenses can be prevented. Inparticular, when the whole of the second lens group is made to be thefocusing lens group, the driving mechanism can be simplified. Moreover,when a portion of the second lens group is made to be the focusing lensgroup, since the focusing lens group can be lightened, response speedfor focusing can be increased.

In an imaging lens according to the first embodiment of the presentapplication, the following conditional expression (2) is preferablysatisfied:

0.015<f2/f1<0.085  (2)

where f1 denotes a focal length of the first lens group, and f2 denotesa focal length of the second lens group.

Conditional expression (2) defines the focal length of the first lensgroup and the focal length of the second lens group. With satisfyingconditional expression (2), an imaging lens according to the firstembodiment of the present application makes it possible to excellentlycorrect curvature of field, spherical aberration, coma and sphericalaberration generated in the first lens group, and coma generated in thesecond lens group.

When the ratio f2/f1 is equal to or exceeds the upper limit ofconditional expression (2), refractive power of the first lens groupbecomes relatively strong, so that it becomes difficult to correctspherical aberration and coma generated in the first lens group alone.Moreover, refractive power of the second lens group becomes relativelyweak, so that curvature of field cannot be excellently corrected.Accordingly, it is undesirable. In order to secure the effect of thepresent application, it is preferable to set the upper limit ofconditional expression (2) to 0.080. In order to further secure theeffect of the present application, it is most preferable to set theupper limit of conditional expression (2) to 0.075.

On the other hand, when the ratio f2/f1 is equal to or falls below thelower limit of conditional expression (2), refractive power of the firstlens group becomes relatively weak, so that correction of sphericalaberration becomes insufficient. Accordingly, it is undesirable.Moreover, refractive power of the second lens group becomes relativelystrong, so that coma generated in the second lens group becomesexcessively large. Accordingly, the purpose of the present applicationto obtain excellent optical performance cannot be achieved. In order tosecure the effect of the present application, it is preferable to setthe lower limit of conditional expression (2) to 0.020. In order tofurther secure the effect of the present application, it is mostpreferable to set the lower limit of conditional expression (2) to0.025.

In an imaging lens according to the first embodiment of the presentapplication, in order to harmonize higher optical performance withcompactness, the second lens group preferably includes at least oneaspherical surface. With this configuration, spherical aberration andcurvature of field can be excellently corrected.

In an imaging lens according to the first embodiment of the presentapplication, the following conditional expression (3) is preferablysatisfied:

0.80<f/f2<1.10  (3)

where f denotes a focal length of the imaging lens, and f2 denotes afocal length of the second lens group.

Conditional expression (3) defines the focal length of the imaging lensand the focal length of the second lens group. With satisfyingconditional expression (3), an imaging lens according to the firstembodiment of the present application makes it possible to excellentlycorrect spherical aberration generated in the second lens group alone.

When the ratio f/f2 is equal to or exceeds the upper limit ofconditional expression (3), refractive power of the second lens groupbecomes strong, so that spherical aberration generated in the secondlens group alone becomes large. Accordingly, it is undesirable. In orderto secure the effect of the present application, it is preferable to setthe upper limit of conditional expression (3) to 1.075. In order tofurther secure the effect of the present application, it is mostpreferable to set the upper limit of conditional expression (3) to 1.05.

On the other hand, when the ratio f/f2 is equal to or falls below thelower limit of conditional expression (3), refractive power of thesecond lens group becomes weak, so that the second lens group does notbecome afocal. Accordingly, when a portion of the imaging lens isshifted in a direction including a component perpendicular to theoptical axis so as to carry out vibration reduction, variation incurvature of field upon vibration reduction becomes large. In order tosecure the effect of the present application, it is preferable to setthe lower limit of conditional expression (3) to 0.85. In order tofurther secure the effect of the present application, it is mostpreferable to set the lower limit of conditional expression (3) to 0.90.

In an imaging lens according to the first embodiment of the presentapplication, in order to harmonize higher optical performance withcompactness, the second lens group preferably includes, in order fromthe object side, a negative meniscus lens having a convex surface facingthe object side, a positive meniscus lens having a convex surface facingthe object side, an aperture stop, a cemented lens constructed by anegative lens having a concave surface facing the object side cementedwith a positive lens having a convex surface facing an image side, and apositive lens. With this configuration, spherical aberration, curvatureof field, and coma can be excellently corrected.

In an imaging lens according to the first embodiment of the presentapplication, the following conditional expression (4) is preferablysatisfied:

2.50<(r3F+r2R)/(r3F−r2R)<3.80  (4)

where r2R denotes a radius of curvature of the image side surface of themost object side lens component in the second lens group, and r3Fdenotes a radius of curvature of a lens surface adjacent to the imageside of the image side surface.

Conditional expression (4) is for excellently correcting coma andcurvature of field generated in the second lens group alone. Withsatisfying conditional expression (4), an imaging lens according to thefirst embodiment of the present application makes it possible tominimally suppress coma and curvature of field generated in the secondlens group alone.

When the value (r3F+r2R)/(r3F−r2R) is equal to or exceeds the upperlimit of conditional expression (4), coma and curvature of fieldgenerated in the second lens group alone cannot be corrected. Moreover,distortion increases, so that it is undesirable. In order to secure theeffect of the present application, it is preferable to set the upperlimit of conditional expression (4) to 3.70. In order to further securethe effect of the present application, it is most preferable to set theupper limit of conditional expression (4) to 3.60.

On the other hand, when the value (r3F+r2R)/(r3F−r2R) is equal to orfalls below the lower limit of conditional expression (4), comagenerated in the second lens group alone becomes excessively large, sothat optical performance upon focusing on a close object becomes worse.Accordingly, it is undesirable. In order to secure the effect of thepresent application, it is preferable to set the lower limit ofconditional expression (4) to 2.60. In order to further secure theeffect of the present application, it is most preferable to set thelower limit of conditional expression (4) to 2.70.

In an imaging lens according to the first embodiment of the presentapplication, in order to harmonize higher optical performance withcompactness, the most object side lens component in the second lensgroup preferably includes at least one aspherical surface. With thisconfiguration, spherical aberration and curvature of field can beexcellently corrected, and higher optical performance and compactnesscan be harmonized.

In an imaging lens according to the first embodiment of the presentapplication, in order to accomplish higher optical performance, theplurality of lens components in the second lens group preferably includeat least one positive lens component, and the most object side positivelens component in the at least one positive lens component preferablyincludes at least one aspherical surface. With this configuration,variations in distortion and curvature of field generated upon focusingcan be excellently corrected.

In an imaging lens according to the first embodiment of the presentapplication, the following conditional expression (5) is preferablysatisfied:

1.55<TL/Σd<1.75  (5)

where TL denotes a total lens length of the imaging lens, and Σd denotesa distance along an optical axis between the most object side lenssurface in the first lens group and the most image side lens surface inthe second lens group.

Conditional expression (5) defines an appropriate total lens length ofthe imaging lens. With satisfying conditional expression (5), an imaginglens according to the first embodiment of the present application makesit possible to harmonize high optical performance with compactness.

When the ratio TL/Ed is equal to or exceeds the upper limit ofconditional expression (5), the total lens length of the imaging lensbecomes large. Accordingly, it becomes impossible to harmonize highoptical performance with compactness, so that it becomes opposite to theintension of the present application. Accordingly, it is undesirable.When the total lens length of the imaging lens is to be secured, comaand curvature of field become worse, so that it is undesirable. In orderto secure the effect of the present application, it is preferable to setthe upper limit of conditional expression (5) to 1.74. In order tofurther secure the effect of the present application, it is mostpreferable to set the upper limit of conditional expression (5) to 1.72.

On the other hand, when the ratio TL/Ed is equal to or falls below thelower limit of conditional expression (5), although it is effective fordownsizing the imaging lens, spherical aberration, coma and curvature offield generated in the whole system of the imaging lens cannot beexcellently corrected, so that it is undesirable. Moreover, the backfocal length cannot be made larger. In order to secure the effect of thepresent application, it is preferable to set the lower limit ofconditional expression (5) to 1.60. In order to further secure theeffect of the present application, it is most preferable to set thelower limit of conditional expression (5) to 1.65.

In an imaging lens according to the first embodiment of the presentapplication, the following conditional expression (6) is preferablysatisfied:

4.00<TL/Ymax<5.00  (6)

where TL denotes a total lens length of the imaging lens, and Ymaxdenotes the maximum image height of the imaging lens.

Conditional expression (6) defines an appropriate total lens length ofthe imaging lens. With satisfying conditional expression (6), an imaginglens according to the first embodiment of the present application makesit possible to harmonize high optical performance with furthercompactness.

When the ratio TL/Ymax is equal to or exceeds the upper limit ofconditional expression (6), the total lens length of the imaging lensbecomes large. Accordingly, it becomes impossible to harmonize highoptical performance with compactness, so that it becomes opposite to theintension of the present application. Accordingly, it is undesirable.When the total lens length of the imaging lens is to be secured, comaand curvature of field become worse, so that it is undesirable. In orderto secure the effect of the present application, it is preferable to setthe upper limit of conditional expression (6) to 4.85. In order tofurther secure the effect of the present application, it is mostpreferable to set the upper limit of conditional expression (6) to 4.70.

On the other hand, when the ratio TL/Ymax is equal to or falls below thelower limit of conditional expression (6), although it is effective fordownsizing, spherical aberration, coma and curvature of field generatedin the whole system of the imaging lens cannot be excellently corrected,so that it is undesirable. In order to secure the effect of the presentapplication, it is preferable to set the lower limit of conditionalexpression (6) to 4.20. In order to further secure the effect of thepresent application, it is most preferable to set the lower limit ofconditional expression (6) to 4.40.

In an imaging lens according to the present application, in order torealize higher optical performance, an aperture stop is preferablydisposed in the second lens group. With this configuration, refractivepower distribution in the second lens group becomes close to a symmetrictype, which is, in order from the object side, a lens group havingpositive refractive power, an aperture stop, and a lens group havingpositive refractive power, so that it becomes possible to excellentlycorrect curvature of field and distortion.

An optical apparatus according to the first embodiment of the presentapplication is characterized by including the imaging lens describedabove. With this configuration, it becomes possible to realize a compactoptical apparatus having a large aperture and a wide angle of view andexcellent optical performance over entire image frame with excellentlycorrecting various aberrations upon focusing on an infinity object to aclose object.

Moreover, a method for manufacturing an imaging lens according to thefirst embodiment of the present application is a method formanufacturing an imaging lens including, in order from an object side, afirst lens group having positive refractive power, and a second lensgroup having positive refractive power, the method comprising steps of:

disposing the second lens group with a plurality of lens components;

disposing the imaging lens with satisfying the following conditionalexpression (1):

0.015<f/f1<0.085  (1)

where f denotes a focal length of the imaging lens, and f1 denotes afocal length of the first lens group; and

fixing a position of the first lens group with respect to an imageplane.

With this method for manufacturing an imaging lens according to thepresent application, it becomes possible to manufacture a compactimaging lens having a large aperture and a wide angle of view andexcellent optical performance over entire image frame with excellentlycorrecting various aberrations upon focusing on an infinity object to aclose object.

Then, an imaging lens, an optical apparatus equipped with the imaginglens, and a method for manufacturing the imaging lens seen from anotherpoint of view according to the first embodiment of the presentapplication are explained below.

An imaging lens seen from another point of view according to the firstembodiment of the present application includes, in order from an objectside, a first lens group having positive refractive power and a secondlens group having positive refractive power. The first lens groupconsists of a single positive lens component having a convex surfacefacing an image side. The second lens group consists of, in order fromthe object side, a negative meniscus lens having a convex surface facingthe object side, a positive lens having a convex surface facing theobject side, an aperture stop, a cemented lens constructed by a negativelens having a concave surface facing the object side cemented with apositive lens having a convex surface facing the image side, and apositive lens. At least a portion of the second lens group is movedalong the optical axis, thereby carrying out focusing from an infinityobject to a close object.

As described above, an imaging lens seen from another point of viewaccording to the first embodiment of the present application includes,in order from an object side, the first lens group having positiverefractive power and the second lens group having positive refractivepower. The first lens group consists of the single positive lenscomponent having a convex surface facing an image side. The second lensgroup consists of, in order from the object side, the negative meniscuslens having a convex surface facing the object side, the positive lenshaving a convex surface facing the object side, the aperture stop, thecemented lens constructed by the negative lens having a concave surfacefacing the object side cemented with the positive lens having a convexsurface facing the image side, and a positive lens. With thisconfiguration, it becomes possible to realize a compact imaging lenshaving a wide-angle of view and excellent optical performance.Incidentally, a lens component is defines as a single lens or a cementedlens constructed by cementing two lenses or more.

As described above, in an imaging lens seen from another point of viewaccording to the first embodiment of the present application, at least aportion of the second lens group is moved along the optical axis,thereby carrying out focusing from an infinity object to a close object.With this configuration, since a moving amount of the focusing lensgroup toward object side upon focusing becomes small, variations inspherical aberration and curvature of field can be excellentlysuppressed. Moreover, interference between lenses and mechanical partsthat holds lenses can be prevented. In particular, when the whole of thesecond lens group is made to be the focusing lens group, the drivingmechanism can be simplified. Moreover, when a portion of the second lensgroup is made to be the focusing lens group, since the focusing lensgroup can be lightened, response speed for focusing can be increased.

With the configuration described above, it becomes possible to realize acompact imaging lens having a large aperture, a wide angle of view andexcellent optical performance over entire image frame with excellentlycorrecting various aberrations upon focusing on an infinity object to aclose object.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, the single positive lenscomponent is preferably a single lens. With this configuration,distortion and curvature of field generated in the imaging lens can beexcellently corrected.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, in order to realize higheroptical performance, the position of the first lens group is preferablyfixed with respect to the image plane. With this configuration,distortion and curvature of field generated in the imaging lens can beexcellently corrected. Moreover, even if external force is inadvertentlyapplied upon using the imaging lens, a moving portion of the imaginglens can be protected.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, the following conditionalexpression (2) is preferably satisfied:

0.015<f2/f1<0.085  (2)

where f1 denotes a focal length of the first lens group, and f2 denotesa focal length of the second lens group.

Conditional expression (2) defines the focal length of the first lensgroup and the focal length of the second lens group. However,conditional expression (2) has already been explained above, so thatduplicated explanations are omitted.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, the following conditionalexpression (1) is preferably satisfied:

0.015<f/f1<0.085  (1)

where f denotes a focal length of the imaging lens, and f1 denotes afocal length of the first lens group.

Conditional expression (1) defines the focal length of the first lensgroup and the focal length of the imaging lens. However, conditionalexpression (1) has already been explained above, so that duplicatedexplanations are omitted.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, the following conditionalexpression (4) is preferably satisfied:

2.50<(r3F+r2R)/(r3F−r2R)<3.80  (4)

where r2R denotes a radius of curvature of the image side surface of themost object side negative meniscus lens in the second lens group, andr3F denotes a radius of curvature of a lens surface adjacent to theimage side of the image side surface.

Conditional expression (4) is for excellently correcting coma andcurvature of field generated in the second lens group alone. However,conditional expression (4) has already been explained above, so thatduplicated explanations are omitted.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, the following conditionalexpression (3) is preferably satisfied:

0.80<f/f2<1.10  (3)

where f denotes a focal length of the imaging lens, and f2 denotes afocal length of the second lens group.

Conditional expression (3) defines the focal length of the imaging lensand the focal length of the second lens group. However, conditionalexpression (3) has already been explained above, so that duplicatedexplanations are omitted.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, the following conditionalexpression (5) is preferably satisfied:

1.55<TL/Σd<1.75  (5)

where TL denotes a total lens length of the imaging lens, and Σd denotesa distance along an optical axis between the most object side lenssurface in the first lens group and the most image side lens surface inthe second lens group.

Conditional expression (5) defines an appropriate total lens length ofthe imaging lens. However, conditional expression (5) has already beenexplained above, so that duplicated explanations are omitted.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, the following conditionalexpression (6) is preferably satisfied:

4.00<TL/Ymax<5.00  (6)

where TL denotes a total lens length of the imaging lens, and Ymaxdenotes the maximum image height of the imaging lens.

Conditional expression (6) defines an appropriate total lens length ofthe imaging lens. However, conditional expression (6) has already beenexplained above, so that duplicated explanations are omitted.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, in order to harmonizehigher optical performance with compactness, the second lens grouppreferably includes at least one aspherical surface. With thisconfiguration, spherical aberration and curvature of field can beexcellently corrected.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, in order to harmonize highoptical performance with compactness, the negative meniscus lensdisposed to the most object side in the second lens group preferablyincludes at least one aspherical surface. With this configuration,spherical aberration and curvature of field can be excellently correctedand high optical performance and compactness can be harmonized.

In an imaging lens seen from another point of view according to thefirst embodiment of the present application, in order to realize higheroptical performance, the positive lens disposed to the most image sidein the second lens group preferably includes at least one asphericalsurface. With this configuration, distortion and curvature of fieldgenerated upon focusing can be excellently corrected.

An optical apparatus seen from another point of view according to thefirst embodiment of the present application is equipped with theabove-described imaging lens. With this configuration, it becomespossible to realize a compact optical apparatus having a large apertureand a wide angle of view and excellent optical performance over entireimage frame with excellently correcting various aberrations uponfocusing on an infinity object to a close object.

Then, a method for manufacturing an imaging lens seen from another pointof view according to the first embodiment of the present application isa method for manufacturing an imaging lens including, in order from anobject side, a first lens group having positive refractive power, and asecond lens group having positive refractive power, the methodcomprising steps of:

disposing the first lens group with a single positive lens componenthaving a convex surface facing an image side;

disposing the second lens group consisting of, in order from the objectside, a negative meniscus lens having a convex surface facing the objectside, a positive lens having a convex surface facing the object side, anaperture stop, a cemented lens constructed by a negative lens having aconcave surface facing the object side cemented with a positive lenshaving a convex surface facing the image side, and a positive lens; and

moving at least a portion of the second lens group along an opticalaxis, thereby carrying out focusing from an infinity object to a closeobject.

With this method for manufacturing an imaging lens seen from anotherpoint of view according to the first embodiment of the presentapplication, it becomes possible to manufacture a compact imaging lenshaving a large aperture and a wide angle of view and excellent opticalperformance over entire image frame with excellently correcting variousaberrations upon focusing on an infinity object to a close object.

Then, an imaging lens according to each numerical example of the firstembodiment of the present application is explained below with referenceto accompanying drawings.

Example 1

FIG. 1 is a sectional view showing a lens configuration of an imaginglens according to Example 1 of the first embodiment of the presentapplication.

As shown in FIG. 1, the imaging lens according to Example 1 is composedof, in order from an unillustrated object side, a first lens group G1having positive refractive power, a second lens group G2 having positiverefractive power disposed with a distance from the first lens group G1,and a filter group FL disposed with a distance from the second lensgroup G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, a positive meniscus lens L22 having a convex surface facing theobject side, a first flare stopper FS1, an aperture stop S, a secondflare stopper FS2, a cemented lens constructed by a double concavenegative lens L23 cemented with a double convex positive lens L24, and adouble convex positive lens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

Incidentally, an unillustrated imaging device composed of a CCD, or aCMOS is disposed on the image plane I. This is the same in the otherExamples explained later.

In the imaging lens according to Example 1, focusing from an infinityobject to a close object is carried out by moving the whole of thesecond lens group G2 along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Various values associated with the imaging lens according to Example 1are listed in Table 1.

In (Specifications) in Table 1, f denotes a focal length, FNO denotes anf-number, 2ω denotes an angle of view (unit: degree), Y denotes an imageheight, TL denotes a total lens length, which is a distance along theoptical axis between the most object side lens surface of the first lensgroup G1 and the image plane I, BF denotes a back focal length, which isa distance along the optical axis between the most image side lenssurface in the second lens group G2 and the image plane I, ACTL denotesan air converted value of the total lens length, and ACBF denotes an airconverted value of the back focal length. In (Lens Data), the left mostcolumn “i” shows an optical surface number counted in order from theobject side, the second column “r” shows a radius of curvature of anoptical surface, the third column “d” shows a distance to the nextoptical surface along an optical axis, the fourth column “nd” shows arefractive index at d-line (wavelength λ=587.6 nm), and the fifth column“νd” shows an Abbe number at d-line (wavelength λ=587.6 nm). In (LensData), an aperture stop S, a first flare stopper FS1, and a second flarestopper FS2 are shown. In the fourth column “nd” refractive index of theair nd=1.000000 is omitted. In the second column “r”, r=^(∞) indicates aplane surface.

An aspherical surface is expressed by the following expression when y isa height in the direction vertical to the optical axis, S(y) is adistance (sag amount) along the optical axis from a tangent plane of avertex of each aspherical surface at the height y up to each asphericalsurface, r is a radius of curvature (paraxial radius of curvature) of areference sphere, k is a conical coefficient and Cn is an n-th orderaspherical surface coefficient.

Note that [E-n] represents [×10 ^(−n)] in the subsequent Examples:

S(y)=(y ² /r)/[1+(1−k×y ² /r ²)^(1/2) ]+C4×y ⁴ +C6×y ⁶ +C8×y ⁸ +C10×y¹⁰.

It should be noted that a second order aspherical surface coefficient C2is “0” in each of Examples.

In (Aspherical Surface Data), “E-n” denotes “×10^(−n)”, in which “n” isan integer, and for example “1.234E-05” denotes “1.234×10⁻⁵”. Eachaspherical surface is expressed in (Lens Data) by attaching “*” to theleft side of the surface number. In (Variable Distances), INF denotesupon focusing on an infinity object, CLD denotes upon focusing on aclose object (shooting rang=0.5 m), and di (i is an integer) denotes thesurface distance of the i-th surface. In (Values for ConditionalExpressions), values for respective conditional expressions are shown.

In respective tables for various values, “mm” is generally used for theunit of length such as the focal length, the radius of curvature and thedistance to the next lens surface. However, since similar opticalperformance can be obtained by an optical system proportionally enlargedor reduced its dimension, the unit is not necessarily to be limited to“mm”, and any other suitable unit can be used.

The explanation of reference symbols is the same in the other Examples.

TABLE 1 (Specifications) f = 10.30 FNO = 2.92 2ω = 78.61 Y = 8.20 TL =37.96 Bf = 15.38 ACTL = 37.01 ACBF = 14.43 (Lens Data) i r d nd νd 1160.5145 1.55 1.48749 70.23 2 −160.5440 d2 3 26.1848 1.10 1.58913 61.16*4 4.8842 3.95 5 9.0140 2.50 1.74950 35.28 6 79.5499 0.30 7 ∞ 1.70 FlareStopper FS1 8 ∞ 1.55 Aperture Stop S 9 ∞ 0.75 Flare Stopper FS2 10−8.6375 1.20 1.80810 22.76 11 113.7348 2.50 1.75500 52.32 12 −10.61650.40 13 21.1214 2.95 1.59201 67.02 *14 −13.9521 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.8842 κ= +0.5528 C4 = +7.2260E−5 C6 = −3.0492E−6 C8 = +2.2154E−7 C10 =−7.9802E−10 Surface Number = 14 r = −13.9521 κ = −11.4868 C4 =−3.0331E−4 C6 = +1.1991E−5 C8 = −1.9031E−7 C10 = +1.4300E−9 (VariableDistances) INF CLD d2 = 2.1334 1.9061 d14 = 10.5166 10.7439 d20 = 0.66440.6644 (Lens Group Data) Group I Focal Length 1 1 164.9097 2 3 9.9988(Values for Conditional Expressions) f = 10.3000 f1 = 164.9097 f2 =9.9988 r2R = 4.8842 r3F = 9.0140 TL = 37.9644 Σd = 22.5834 Ymax = 8.2000(1) f/f1 = 0.0625 (2) f2/f1 = 0.0606 (3) f/f2 = 1.0301 (4) (r3F +r2R)/(r3F − r2R) = 3.3653 (5) TL/Σd = 1.6811 (6) TL/Ymax = 4.6298

FIGS. 2A and 2B are graphs showing various aberrations of the imaginglens according to Example 1, in which FIG. 2A is upon focusing oninfinity, and FIG. 2B is upon focusing on a close shooting distance.

In respective graphs, FNO denotes an f-number, A denotes a half angle ofview, NA denotes a numerical aperture, HO denotes an object height. Ingraphs showing astigmatism, a solid line indicates a sagittal imageplane, and a broken line indicates a meridional image plane. Theexplanations of reference symbols are the same in the other Examples.

As is apparent from various graphs, the imaging lens according toExample 1 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object.

Example 2

FIG. 3 is a sectional view showing a lens configuration of an imaginglens according to Example 2 of the present application.

As shown in FIG. 3, the imaging lens according to Example 2 is composedof, in order from an unillustrated object side, a first lens group G1having positive refractive power, a second lens group G2 having positiverefractive power disposed with a distance from the first lens group G1,and a filter group FL disposed with a distance from the second lensgroup G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, a positive meniscus lens L22 having a convex surface facing theobject side, a first flare stopper FS1, an aperture stop S, a secondflare stopper FS2, a cemented lens constructed by a double concavenegative lens L23 cemented with a double convex positive lens L24, and adouble convex positive lens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 2, focusing from an infinityobject to a close object is carried out by moving a portion of thesecond lens group G2, in particular, a cemented lens constructed by thenegative lens L23 cemented with the positive lens L24, and the positivelens L25 in a body along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Various values associated with the imaging lens according to Example 2are listed in Table 2.

TABLE 2 (Specifications) f = 10.30 FNO = 2.92 2ω = 78.60 Y = 8.20 TL =37.97 BF = 15.46 ACTL = 37.02 ACBF = 14.51 (Lens Data) i r d nd νd 1346.0582 1.20 1.60300 65.44 2 −346.0893 d2 3 24.3607 1.20 1.58313 59.38*4 4.6967 3.70 5 9.3473 2.90 1.74950 35.28 6 305.1987 0.30 7 ∞ 1.70Flare Stopper FS1 8 ∞ 1.40 Aperture Stop S 9 ∞ d9 Flare Stopper FS2 10−9.2201 1.00 1.80810 22.76 11 77.4450 2.70 1.75500 52.32 12 −10.98300.40 13 25.7154 2.95 1.59201 67.02 *14 −12.9856 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.6967 κ= +0.1147 C4 = +5.5141E−4 C6 = +3.4495E−6 C8 = +3.3752E−7 C10 =−9.7228E−10 Surface Number = 14 r = −12.9856 κ = −10.9391 C4 =−4.1228E−4 C6 = +1.5051E−5 C8 = −2.5702E−7 C10 = +2.1453E−9 (VariableDistances) INF CLD d2 = 2.1557 2.1557 d9 = 0.9000 0.6716 d14 = 10.563710.7921 d20 = 0.7000 0.7000 (Lens Group Data) Group I Focal Length 1 1287.1468 2 3 10.1322 (Values for Conditional Expressions) f = 10.3000 f1= 287.1468 f2 = 10.1322 r2R = 4.6967 r3F = 9.3473 TL = 37.9694 Σd =22.5057 Ymax = 8.2000 (1) f/f1 = 0.0359 (2) f2/f1 = 0.0353 (3) f/f2 =1.0166 (4) (r3F + r2R)/(r3F − r2R) = 3.0199 (5) TL/Σd = 1.6871 (6)TL/Ymax = 4.6304

FIGS. 4A and 4B are graphs showing various aberrations of the imaginglens according to Example 2, in which FIG. 4A is upon focusing oninfinity, and FIG. 4B is upon focusing on a close shooting distance.

As is apparent from various graphs, the imaging lens according toExample 2 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object.

Example 3

FIG. 5 is a sectional view showing a lens configuration of an imaginglens according to Example 3 of the present application.

As shown in FIG. 5, the imaging lens according to Example 3 is composedof, in order from an unillustrated object side, a first lens group G1having positive refractive power, a second lens group G2 having positiverefractive power disposed with a distance from the first lens group G1,and a filter group FL disposed with a distance from the second lensgroup G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, a positive meniscus lens L22 having a convex surface facing theobject side, a first flare stopper FS1, an aperture stop S, a secondflare stopper FS2, a cemented lens constructed by a double concavenegative lens L23 cemented with a double convex positive lens L24, and adouble convex positive lens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 3, focusing from an infinityobject to a close object is carried out by moving the whole of thesecond lens group G2 along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Various values associated with the imaging lens according to Example 3are listed in Table 3.

TABLE 3 (Specifications) f = 10.30 FNO = 2.91 2ω = 78.62 Y = 8.20 TL =37.57 BF = 15.47 ACTL = 36.62 ACBF = 14.52 (Lens Data) i r d nd νd 1332.7704 1.00 1.60300 65.44 2 −332.7936 d2 3 22.0308 1.10 1.58313 59.38*4 4.5012 3.45 5 9.0325 3.05 1.74950 35.28 6 117.5529 0.30 7 ∞ 1.70Flare Stopper FS1 8 ∞ 1.60 Aperture Stop S 9 ∞ 0.70 Flare Stopper FS2 10−10.0955 1.00 1.80810 22.76 11 52.5077 2.70 1.75500 52.32 12 −11.59740.40 13 24.8237 2.97 1.59201 67.05 *14 −12.8447 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.5012 κ= +0.3479 C4 = +3.0704E−4 C6 = +9.9005E−7 C8 = +3.7811E−7 C10 =−1.2499E−9 Surface Number = 14 r = −12.8447 κ = −10.3357 C4 = −4.0200E−4C6 = +1.4415E−5 C8 = −2.4522E−7 C10 = +2.0151E−9 (Variable Distances)INF CLD d2 = 2.1344 1.9074 d14 = 10.6000 10.8270 d20 = 0.6652 0.6652(Lens Group Data) Group I Focal Length 1 1 276.0942 2 3 10.1310 (Valuesfor Conditional Expressions) f = 10.2975 f1 = 276.0942 f2 = 10.1310 r2R= 4.5012 r3F = 9.0325 TL = 37.5652 Σd = 22.1000 Ymax = 8.2000 (1) f/f1 =0.0373 (2) f2/f1 = 0.0367 (3) f/f2 = 1.0164 (4) (r3F + r2R)/(r3F − r2R)= 2.9867 (5) TL/Σd = 1.6998 (6) TL/Ymax = 4.5811

FIGS. 6A and 6B are graphs showing various aberrations of the imaginglens according to Example 3, in which FIG. 6A is upon focusing oninfinity, and FIG. 6B is upon focusing on a close shooting distance.

As is apparent from various graphs, the imaging lens according toExample 3 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object.

Example 4

FIG. 7 is a sectional view showing a lens configuration of an imaginglens according to Example 4 of the present application.

As shown in FIG. 7, the imaging lens according to Example 4 is composedof, in order from an unillustrated object side, a first lens group G1having positive refractive power, a second lens group G2 having positiverefractive power disposed with a distance from the first lens group G1,and a filter group FL disposed with a distance from the second lensgroup G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, a positive meniscus lens L22 having a convex surface facing theobject side, a first flare stopper FS1, an aperture stop S, a secondflare stopper FS2, a cemented lens constructed by a double concavenegative lens L23 cemented with a double convex positive lens L24, and adouble convex positive lens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 4, focusing from an infinityobject to a close object is carried out by moving the whole of thesecond lens group G2 along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Various values associated with the imaging lens according to Example 4are listed in Table 4.

TABLE 4 (Specifications) f = 10.30 FNO = 2.89 2ω = 78.61 Y = 8.20 TL =37.47 BF = 15.38 ACTL = 36.52 ACBF = 14.43 (Lens Data) i r d nd νd 1290.4936 1.00 1.51680 64.11 2 −290.7707 d2 3 19.6032 1.10 1.58913 61.15*4 4.4561 3.25 5 9.1671 3.75 1.74950 35.28 6 79.1129 0.30 7 ∞ 1.70 FlareStopper FS1 8 ∞ 1.05 Aperture Stop S 9 ∞ 1.25 Flare Stopper FS2 10−11.3274 1.15 1.80810 22.76 11 44.4829 2.75 1.75500 52.32 12 −11.52210.50 13 23.9759 3.00 1.59201 67.02 *14 −14.2191 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.4561 κ= +0.6048 C4 = −2.4225E−5 C6 = −1.1037E−5 C8 = +5.0943E−7 C10 =−1.8920E−8 Surface Number = 14 r = −14.2191 κ = −11.3728 C4 = −3.1719E−4C6 = +1.0532E−5 C8 = −1.6628E−7 C10 = +1.2559E−9 (Variable Distances)INF CLD d2 = 1.2865 1.0592 d14 = 10.5135 10.7408 d20 = 0.6702 0.6702(Lens Group Data) Group I Focal Length 1 1 281.3493 2 3 10.1574 (Valuesfor Conditional Expressions) f = 10.3000 f1 = 281.3493 f2 = 10.1574 r2R= 4.4561 r3F = 9.1671 TL = 37.4702 Σd = 22.0865 Ymax = 8.2000 (1) f/f1 =0.0366 (2) f2/f1 = 0.0361 (3) f/f2 = 1.0140 (4) (r3F + r2R)/(r3F − r2R)= 2.8917 (5) TL/Σd = 1.6965 (6) TL/Ymax = 4.5695

FIGS. 8A and 8B are graphs showing various aberrations of the imaginglens according to Example 4, in which FIG. 8A is upon focusing oninfinity, and FIG. 8B is upon focusing on a close shooting distance.

As is apparent from various graphs, the imaging lens according toExample 4 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object.

Example 5

FIG. 9 is a sectional view showing a lens configuration of an imaginglens according to Example 5 of the present application.

As shown in FIG. 9, the imaging lens according to Example 5 is composedof, in order from an unillustrated object side, a first lens group G1having positive refractive power, a second lens group G2 having positiverefractive power disposed with a distance from the first lens group G1,and a filter group FL disposed with a distance from the second lensgroup G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, a positive meniscus lens L22 having a convex surface facing theobject side, a first flare stopper FS1, an aperture stop S, a secondflare stopper FS2, a cemented lens constructed by a double concavenegative lens L23 cemented with a double convex positive lens L24, and adouble convex positive lens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 5, focusing from an infinityobject to a close object is carried out by moving a portion of thesecond lens group G2, in particular, a cemented lens constructed by thenegative lens L23 cemented with the positive lens L24, and the positivelens L25 in a body along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Various values associated with the imaging lens according to Example 5are listed in Table 5.

TABLE 5 (Specifications) f = 10.30 FNO = 2.92 2ω = 78.60 Y = 8.20 TL =37.45 BF = 15.52 ACTL = 36.50 ACBF = 14.57 (Lens Data) i r d nd νd 1367.5465 1.00 1.60300 65.44 2 −368.4597 d2 3 21.2966 1.10 1.58313 59.38*4 4.4652 3.35 5 9.2118 3.50 1.74950 35.28 6 129.9098 0.30 7 ∞ 1.70Flare Stopper FS1 8 ∞ 1.60 Aperture Stop S 9 ∞ d9 Flare Stopper FS2 10−10.7870 1.10 1.80810 22.76 11 46.2743 2.75 1.75500 52.32 12 −11.64410.40 13 25.7948 2.95 1.59201 67.02 *14 −13.3762 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.4652 κ= +0.3656 C4 = +2.6809E−4 C6 = +1.6171E−6 C8 = +2.8446E−7 C10 =+2.2563E−10 Surface Number = 14 r = −13.3762 κ = −11.1665 C4 =−3.9072E−4 C6 = +1.3411E−5 C8 = −2.2460E−7 C10 = +1.8090E−9 (VariableDistances) INF CLD d2 = 1.4850 1.4850 d9 = 0.7000 0.4728 d14 = 10.648910.8762 d20 = 0.6663 0.6663 (Lens Group Data) Group I Focal Length 1 1305.2986 2 3 10.1676 (Values for Conditional Expressions) f = 10.3000 f1= 305.2986 f2 = 10.1676 r2R = 4.4652 r3F = 9.2118 TL = 37.4502 Σd =21.9350 Ymax = 8.2000 (1) f/f1 = 0.0337 (2) f2/f1 = 0.0333 (3) f/f2 =1.0130 (4) (r3F + r2R)/(r3F − r2R) = 2.8814 (5) TL/Σd = 1.7073 (6)TL/Ymax = 4.5671

FIGS. 10A and 10B are graphs showing various aberrations of the imaginglens according to Example 5, in which FIG. 10A is upon focusing oninfinity, and FIG. 10B is upon focusing on a close shooting distance.

As is apparent from various graphs, the imaging lens according toExample 5 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object.

Example 6

FIG. 11 is a sectional view showing a lens configuration of an imaginglens according to Example 6 of the present application.

As shown in FIG. 11, the imaging lens according to Example 6 is composedof, in order from an unillustrated object side, a first lens group G1having positive refractive power, a second lens group G2 having positiverefractive power disposed with a distance from the first lens group G1,and a filter group FL disposed with a distance from the second lensgroup G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, a positive meniscus lens L22 having a convex surface facing theobject side, a first flare stopper FS1, an aperture stop S, a secondflare stopper FS2, a cemented lens constructed by a double concavenegative lens L23 cemented with a double convex positive lens L24, and adouble convex positive lens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 6, focusing from an infinityobject to a close object is carried out by moving the whole of thesecond lens group G2 along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Various values associated with the imaging lens according to Example 6are listed in Table 6.

TABLE 6 (Specifications) f = 10.30 FNO = 2.91 2ω = 78.61 Y = 8.20 TL =37.79 BF = 15.45 ACTL = 36.84 ACBF = 14.50 (Lens Data) i r d nd νd 1160.4134 1.52 1.51633 64.14 2 −160.4538 d2 3 23.9005 1.10 1.58313 59.38*4 4.4680 3.19 5 8.8845 3.00 1.74950 35.28 6 59.7352 0.30 7 ∞ 1.70 FlareStopper FS1 8 ∞ 1.05 Aperture Stop S 9 ∞ 1.25 Flare Stopper FS2 10−10.3948 1.00 1.80810 22.76 11 53.0153 2.70 1.75500 52.32 12 −10.81130.40 13 22.9281 2.99 1.59201 67.05 *14 −14.0952 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.4680 κ= +0.4037 C4 = +2.7434E−4 C6 = +4.0423E−6 C8 = +1.7001E−7 C10 =+1.0858E−8 Surface Number = 14 r = −14.0952 κ = −11.0203 C4 = −3.0335E−4C6 = +1.0309E−5 C8 = −1.5359E−7 C10 = +1.0836E−9 (Variable Distances)INF CLD d2 = 2.1336 1.9062 d14 = 10.5627 10.7901 d20 = 0.6862 0.6862(Lens Group Data) Group I Focal Length 1 1 155.6106 2 3 9.9966 (Valuesfor Conditional Expressions) f = 10.3014 f1 = 155.6106 f2 = 9.9966 r2R =4.4680 r3F = 8.8845 TL = 37.7862 Σd = 22.3373 Ymax = 8.2000 (1) f/f1 =0.0662 (2) f2/f1 = 0.0642 (3) f/f2 = 1.0305 (4) (r3F + r2R)/(r3F − r2R)= 3.0233 (5) TL/Σd = 1.6916 (6) TL/Ymax = 4.6081

FIGS. 12A and 12B are graphs showing various aberrations of the imaginglens according to Example 6, in which FIG. 12A is upon focusing oninfinity, and FIG. 12B is upon focusing on a close shooting distance.

As is apparent from various graphs, the imaging lens according toExample 6 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object.

Example 7

FIG. 13 is a sectional view showing a lens configuration of an imaginglens according to Example 7 of the present application.

As shown in FIG. 13, the imaging lens according to Example 7 is composedof, in order from an unillustrated object side, a first lens group G1having positive refractive power, a second lens group G2 having positiverefractive power disposed with a distance from the first lens group G1,and a filter group FL disposed with a distance from the second lensgroup G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, a positive meniscus lens L22 having a convex surface facing theobject side, a first flare stopper FS1, an aperture stop S, a secondflare stopper FS2, a cemented lens constructed by a double concavenegative lens L23 cemented with a double convex positive lens L24, and adouble convex positive lens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 7, focusing from an infinityobject to a close object is carried out by moving the whole of thesecond lens group G2 along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Various values associated with the imaging lens according to Example 7are listed in Table 7.

TABLE 7 (Specifications) f = 10.30 FNO = 2.94 2ω = 78.61 Y = 8.20 TL =37.86 BF = 15.56 ACTL = 36.91 ACBF = 14.61 (Lens Data) i r d nd νd 1307.5313 1.20 1.48749 70.23 2 −307.5947 d2 3 21.9567 1.10 1.58313 59.38*4 4.5581 3.45 5 9.6306 3.05 1.74950 35.28 6 292.4663 0.30 7 ∞ 1.70Flare Stopper FS1 8 ∞ 1.05 Aperture Stop S 9 ∞ 1.25 Flare Stopper FS2 10−8.9112 1.00 1.80810 22.76 11 506.5428 2.70 1.75500 52.32 12 −9.37930.40 13 21.0314 2.97 1.49700 81.61 *14 −13.3938 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.5581 κ= +0.1979 C4 = +4.8517E−4 C6 = +5.1785E−6 C8 = +2.7432E−7 C10 =+2.0130E−9 Surface Number = 14 r = −13.3938 κ = −12.8217 C4 = −4.2055E−4C6 = +1.6915E−5 C8 = −2.9730E−7 C10 = +2.4991E−9 (Variable Distances)INF CLD d2 = 2.1354 1.9083 d14 = 10.6990 10.9261 d20 = 0.6645 0.6645(Lens Group Data) Group I Focal Length 1 1 315.6575 2 3 10.1518 (Valuesfor Conditional Expressions) f = 10.3000 f1 = 315.6575 f2 = 10.1518 r2R= 4.5581 r3F = 9.6306 TL = 37.8645 Σd = 22.3010 Ymax = 8.2000 (1) f/f1 =0.0326 (2) f2/f1 = 0.0322 (3) f/f2 = 1.0146 (4) (r3F + r2R)/(r3F − r2R)= 2.7972 (5) TL/Σd = 1.6979 (6) TL/Ymax = 4.6176

FIGS. 14A and 14B are graphs showing various aberrations of the imaginglens according to Example 7, in which FIG. 14A is upon focusing oninfinity, and FIG. 14B is upon focusing on a close shooting distance.

As is apparent from various graphs, the imaging lens according toExample 6 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object.

Each example described above makes it possible to provide a compactimaging lens having a wide angle of view of 60 degrees or more, a largeaperture of an f-number of about 2.8 and excellent optical performanceover entire image frame with excellently correcting various aberrationsupon focusing on an infinity object to a close object.

In an imaging lens according to each Example, a back focal length, whichis a distance along the optical axis between the image side lens surfaceof a lens disposed to the most image side and the image plane, ispreferably from about 10.0 mm to 30.0 mm in the smallest state.Moreover, in an imaging lens according to each Example, the image heightis preferably 5.0 mm to 12.5 mm, and most preferably 5.0 mm to 9.5 mm.

Then, an outline of a method for manufacturing an imaging lens accordingto the first embodiment of the present application is explained belowwith reference to FIG. 31.

FIG. 31 is a flowchart showing a method for manufacturing an imaginglens according to the present embodiment.

The method for manufacturing an imaging lens is a method formanufacturing an imaging lens including, in order from an object side, afirst lens group having positive refractive power and a second lensgroup having positive refractive, the method includes the followingsteps S1 through S3:

Step S1: disposing the second lens group with a plurality of lenscomponents;

Step S2: disposing the imaging lens with satisfying the followingconditional expression (1):

0.015<f/f1<0.085  (1)

where f denotes a focal length of the imaging lens, and f1 denotes afocal length of the first lens group; and

Step S3: fixing a position of the first lens group with respect to animage plane.

With the method for manufacturing an imaging lens according to thepresent application, it becomes possible to manufacture a compactimaging lens having a wide angle of view, a large aperture and excellentoptical performance over entire image frame with excellently correctingvarious aberrations upon focusing on an infinity object to a closeobject.

Then, an outline of a method for manufacturing an imaging lens seen fromanother point of view according to the first embodiment of the presentapplication is explained below with reference to FIG. 32.

FIG. 32 is a flowchart showing a method for manufacturing an imaginglens seen from another point of view according to the first embodimentof the present application.

The method for manufacturing an imaging lens seen from another point ofview according to the first embodiment is a method for manufacturing animaging lens including, in order from an object side, a first lens grouphaving positive refractive power and a second lens group having positiverefractive, the method includes the following steps S11 through S13:

Step S11: disposing the first lens group with a single positive lenscomponent having a convex surface facing an image side;

Step S12: disposing the second lens group consisting of, in order fromthe object side, a negative meniscus lens having a convex surface facingthe object side, a positive lens having a convex surface facing theobject side, an aperture stop, a cemented lens constructed by a negativelens having a concave surface facing the object side cemented with apositive lens having a convex surface facing the image side, and apositive lens into a lens barrel in order from the object side; and

Step S13: moving the whole or a portion of the second lens group alongan optical axis by providing a well-known moving mechanism in the lensbarrel, thereby carrying out focusing from an infinity object to a closeobject.

With this method for manufacturing an imaging lens seen from anotherpoint of view according to the first embodiment of the presentapplication, it becomes possible to manufacture a compact imaging lenshaving a wide angle of view, a large aperture and excellent opticalperformance over entire image frame with excellently correcting variousaberrations upon focusing on an infinity object to a close object.

Second Embodiment

Then, an imaging lens, an optical apparatus equipped with the imaginglens, and a method for manufacturing the imaging lens according to asecond embodiment of the present application are explained below.

An imaging lens according to the second embodiment of the presentapplication includes, in order from an object side, a first lens grouphaving positive refractive power, and a second lens group havingpositive refractive power. The first lens group consists of a singlelens component. The second lens group consists of, in order from theobject side, a front lens group, an aperture stop, and a rear lensgroup. The whole or the rear lens group of the second lens group ismoved as a shift lens group in a direction including a componentperpendicular to an optical axis.

As described above, an imaging lens according to the second embodimentof the present application includes, in order from the object side, thefirst lens group having positive refractive power, and the second lensgroup having positive refractive power. The first lens group consists ofa single lens component. The second lens group consists of, in orderfrom the object side, the front lens group, the aperture stop, and therear lens group. With this configuration, it becomes possible to realizea compact imaging lens having a wide angle of view and high opticalperformance. In particular, the second lens group becomes close to asymmetric type refractive power distribution, which is, in order fromthe object side, the front lens group, the aperture stop, and the rearlens group, so that it becomes possible to excellently correct curvatureof field and distortion. Incidentally, a lens component is defined as asingle lens or a cemented lens constructed by cementing two lenses ormore.

Moreover, at least a portion of the second lens group is moved as ashift lens group in a direction including a component perpendicular tothe optical axis so as to shifting the image, thereby correcting animage blur caused by a camera shake (vibration reduction). Inparticular, when the whole of the second lens group is made to be theshift lens group, driving mechanism can be simplified. Moreover, whenthe rear lens group in the second lens group is made to be the shiftlens group, since the shift lens group can be lightened, response speedupon vibration reduction can be increased.

With this configuration, it becomes possible to excellently correctvarious aberrations and realize a compact imaging lens having excellentoptical performance over entire image frame with minimally suppressingdeterioration in optical performance upon vibration reduction.

In an imaging lens according to the second embodiment of the presentapplication, the following conditional expression (7) is preferablysatisfied:

0.00<f2R/|f2F|<0.20  (7)

where f2F denotes a focal length of the front lens group, and f2Rdenotes a focal length of the rear lens group.

Conditional expression (7) defines the focal length of the front lensgroup and the focal length of the rear lens group. With satisfyingconditional expression (7), an imaging lens seen from another point ofview according to the present application makes it possible toexcellently correct curvature of field, spherical aberration, coma andspherical aberration generated in the front lens group alone, and comagenerated in the second lens group.

When the ratio f2R/|f2F| is equal to or exceeds the upper limit ofconditional expression (7), refractive power of the front lens groupbecomes relatively strong, so that it becomes difficult to correctspherical aberration and coma generated in the front lens group alone.Moreover, refractive power of the rear lens group becomes relativelyweak, so that it becomes difficult to correct curvature of field.Accordingly, it is undesirable. In order to secure the effect of thepresent application, it is preferable to set the upper limit ofconditional expression (7) to 0.17. In order to further secure theeffect of the present application, it is most preferable to set theupper limit of conditional expression (7) to 0.15.

On the other hand, when the ratio f2R/|f2F| is equal to or falls belowthe lower limit of conditional expression (7), refractive power of thefront lens group becomes relatively weak, correction of sphericalaberration becomes insufficient, so that it is undesirable. Moreover,refractive power of the rear lens group becomes relatively strong, sothat coma generated in the second lens group becomes excessively large.Accordingly, the purpose of the present application to obtain excellentoptical performance cannot be realized. In order to secure the effect ofthe present application, it is preferable to set the lower limit ofconditional expression (7) to 0.003. In order to further secure theeffect of the present application, it is most preferable to set thelower limit of conditional expression (7) to 0.005.

In an imaging lens according to the second embodiment of the presentapplication, in order to obtain higher optical performance, the rearlens group preferably includes, in order from the object side, acemented lens constructed by a negative lens having a concave surfacefacing the object side cemented with a positive lens having a convexsurface facing an image side, and a double convex positive lens. Withthis configuration, it becomes possible to excellently correct curvatureof field and coma.

In an imaging lens according to the second embodiment of the presentapplication, at least a portion of the second lens group is preferablymoved as a focusing lens group along the optical axis, thereby carryingout focusing from an infinity object to a close object. With thisconfiguration, a moving amount of the focusing lens group toward theobject upon focusing becomes extremely small, so that variations inspherical aberration and curvature of field can be excellentlysuppressed. Moreover, interference between lenses and mechanical partsthat holds lenses can be prevented.

In an imaging lens according to the second embodiment of the presentapplication, in order to harmonize high optical performance withcompactness, the front lens group preferably includes, in order from theobject side, a negative meniscus lens having a convex surface facing theobject side, and a positive meniscus lens having a convex surface facingthe object side. With this configuration, it becomes possible toexcellently correct spherical aberration and curvature of fieldgenerated in the front lens group alone.

In an imaging lens according to the second embodiment of the presentapplication, the front lens group preferably includes a plurality oflens components, and the following conditional expression (4) ispreferably satisfied:

2.50<(r3F+r2R)/(r3F−r2R)<3.80  (4)

where r2R denotes a radius of curvature of the image side lens surfaceof a lens component disposed to the most object side in the front lensgroup, and r3F denotes a radius of curvature of a lens surface adjacentto the image side of the image side lens surface.

Conditional expression (4) is for excellently correcting coma andcurvature of field generated in the second lens group alone. However,conditional expression (4) has already been explained above, so thatduplicated explanations are omitted.

In an imaging lens according to the second embodiment of the presentapplication, the following conditional expression (5) is preferablysatisfied:

1.55<TL/Σd<1.75  (5)

where TL denotes a total lens length of the imaging lens, and Σd denotesa distance along an optical axis between the most object side lenssurface in the first lens group and the most image side lens surface inthe second lens group.

Conditional expression (5) defines an appropriate total lens length ofthe imaging lens. However, conditional expression (5) has already beenexplained above, so that duplicated explanations are omitted.

In an imaging lens according to the second embodiment of the presentapplication, the following conditional expression (6) is preferablysatisfied:

4.00<TL/Ymax<5.00  (6)

where TL denotes a total lens length of the imaging lens, and Ymaxdenotes the maximum image height of the imaging lens.

Conditional expression (6) defines an appropriate total lens length ofthe imaging lens. However, conditional expression (6) has already beenexplained above, so that duplicated explanations are omitted.

In an imaging lens according to the second embodiment of the presentapplication, the following conditional expression (2) is preferablysatisfied:

0.015<f2/f1<0.085  (2)

where f1 denotes a focal length of the first lens group, and f2 denotesa focal length of the second lens group.

Conditional expression (2) defines the focal length of the first lensgroup and the focal length of the second lens group. However,conditional expression (2) has already been explained above, so thatduplicated explanations are omitted.

In an imaging lens according to the second embodiment of the presentapplication, the following conditional expression (8) is preferablysatisfied:

0.70<f/f2R<0.85  (8)

where f denotes a focal length of the imaging lens, and f2R denotes afocal length of the rear lens group.

Conditional expression (8) defines the focal length of the imaging lensand the focal length of the rear lens group. With satisfying conditionalexpression (8), an imaging lens seen from another point of viewaccording to the present application makes it possible to suppressvariation in curvature of field upon vibration reduction withexcellently correcting spherical aberration generated in the rear lensgroup alone.

When the ratio f/f2R is equal to or exceeds the upper limit ofconditional expression (8), refractive power of the rear lens groupbecomes strong, so that spherical aberration generated in the rear lensgroup alone becomes large. Accordingly, it is undesirable. In order tosecure the effect of the present application, it is preferable to setthe upper limit of conditional expression (8) to 0.83. In order tofurther secure the effect of the present application, it is mostpreferable to set the upper limit of conditional expression (8) to 0.82.

On the other hand, when the ratio f/f2R is equal to or falls below thelower limit of conditional expression (8), refractive power of the rearlens group becomes weak, so that the rear lens group does not becomeafocal. Accordingly, variation in curvature of field upon vibrationreduction becomes large. In order to secure the effect of the presentapplication, it is preferable to set the lower limit of conditionalexpression (8) to 0.72. In order to further secure the effect of thepresent application, it is most preferable to set the lower limit ofconditional expression (8) to 0.74.

In an imaging lens according to the second embodiment of the presentapplication, in order to realize higher optical performance, the firstlens group preferably consists of a positive lens having a convexsurface facing the object side. With this configuration, it becomespossible to excellently correct distortion and curvature of fieldgenerated in the whole system of the imaging lens.

In an imaging lens according to the second embodiment of the presentapplication, in order to realize higher optical performance, theposition of the first lens group is preferably fixed with respect to theimage plane. With this configuration, it becomes possible to excellentlycorrect distortion and curvature of field generated in the whole systemof the imaging lens. Moreover, even if external force is inadvertentlyapplied upon using the imaging lens, a moving portion of the imaginglens can be protected.

In an imaging lens according to the second embodiment of the presentapplication, the following conditional expression (1) is preferablysatisfied:

0.015<f/f1<0.085  (1)

where f denotes a focal length of the imaging lens, and f1 denotes afocal length of the first lens group.

Conditional expression (1) defines the focal length of the first lensgroup and the focal length of the imaging lens. However, conditionalexpression (1) has already been explained above, so that duplicatedexplanations are omitted.

In an imaging lens according to the second embodiment of the presentapplication, in order to harmonize higher optical performance withcompactness, the front lens group preferably includes at least oneaspherical surface. With this configuration, spherical aberration andcurvature of field can be excellently corrected.

In an imaging lens according to the second embodiment of the presentapplication, in order to harmonize high optical performance withcompactness, the front lens group preferably includes a plurality oflens components, and the most object side lens component in the firstlens group preferably includes at least one aspherical surface. Withthis configuration, spherical aberration and curvature of field can beexcellently corrected and higher optical performance and compactness canbe harmonized.

In an imaging lens according to the second embodiment of the presentapplication, in order to harmonize higher optical performance withcompactness, the rear lens group preferably includes at least oneaspherical surface. With this configuration, distortion and curvature offield can be excellently corrected.

In an imaging lens according to the second embodiment of the presentapplication, in order to realize higher optical performance, it ispreferable that the rear lens group includes a plurality of lenscomponents and the most image side lens component in the rear lens groupincludes at least one aspherical surface. With this configuration,distortion and curvature of field generated upon focusing can beexcellently corrected.

An optical apparatus according to the second embodiment of the presentapplication is equipped with the above-described imaging lens. With thisconfiguration, it becomes possible to realize a compact opticalapparatus capable of correcting various aberrations, suppressingdeterioration in optical performance minimally upon vibration reduction,and having excellent optical performance over entire image frame.

Then, a method for manufacturing an imaging lens according to the secondembodiment of the present application is a method for manufacturing animaging lens including, in order from an object side, a first lens grouphaving positive refractive power, and a second lens group havingpositive refractive power, the method comprising steps of:

disposing the first lens group with a single lens component;

disposing the second lens group consisting of, in order from the objectside, a front lens group, an aperture stop, and a rear lens group; and

moving the whole of the second lens group or the rear lens group as ashift lens group in a direction including a component perpendicular toan optical axis.

With this method for manufacturing an imaging lens according to thesecond embodiment of the present application, it becomes possible tomanufacture a compact imaging lens capable of correcting variousaberrations, suppressing deterioration in optical performance minimallyupon vibration reduction, and having excellent optical performance overentire image frame.

Then, an imaging lens according to each numerical example of the secondembodiment of the present application is explained below with referenceto accompanying drawings.

Example 8

FIG. 15 is a sectional view showing a lens configuration of an imaginglens according to Example 8 of the second embodiment of the presentapplication.

As shown in FIG. 15, the imaging lens according to Example 8 is composedof, in order from an unillustrated object side, a first lens group G1having positive refractive power, a second lens group G2 having positiverefractive power disposed with a distance from the first lens group G1,and a filter group FL disposed with a distance from the second lensgroup G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a front lens group G2F having positive refractive power, a first flarestopper FS1, an aperture stop S, a second flare stopper FS2, and a rearlens group G2R having positive refractive power.

The front lens group G2F is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, and a positive meniscus lens L22 having a convex surface facingthe object side.

The rear lens group G2R is composed of, in order from the object side, acemented lens constructed by a double concave negative lens L23 cementedwith a double convex positive lens L24, and a double convex positivelens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 8, focusing from an infinityobject to a close object is carried out by moving the whole of thesecond lens group G2 along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Moreover, in the imaging lens according to Example 8, the whole of thesecond lens group is moved as a shift lens group in a directionincluding a component perpendicular to the optical axis, therebycorrecting an image blur upon generating a camera shake.

Various values associated with the imaging lens according to Example 8are listed in Table 8.

TABLE 8 (Specifications) f = 10.30 FNO = 2.92 2ω = 78.61 Y = 8.20 TL =37.96 Bf = 15.38 ACTL = 37.01 ACBF = 14.43 (Lens Data) i r d nd νd 1160.5145 1.55 1.48749 70.23 2 −160.5440 d2 3 26.1848 1.10 1.58913 61.16*4 4.8842 3.95 5 9.0140 2.50 1.74950 35.28 6 79.5499 0.30 7 ∞ 1.70 FlareStopper FS1 8 ∞ 1.55 Aperture Stop S 9 ∞ 0.75 Flare Stopper FS2 10−8.6375 1.20 1.80810 22.76 11 113.7348 2.50 1.75500 52.32 12 −10.61650.40 13 21.1214 2.95 1.59201 67.02 *14 −13.9521 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.8842 κ= +0.5528 C4 = +7.2260E−5 C6 = −3.0492E−6 C8 = +2.2154E−7 C10 =−7.9802E−10 Surface Number = 14 r = −13.9521 κ = −11.4868 C4 =−3.0331E−4 C6 = +1.1991E−5 C8 = −1.9031E−7 C10 = +1.4300E−9 (VariableDistances) INF CLD d2 = 2.1334 1.9061 d14 = 10.5166 10.7439 d20 = 0.66440.6644 (Lens Group Data) Group I Focal Length 1 1 164.9097 2 3 9.9988(Values for Conditional Expressions) f = 10.3000 f1 = 164.9097 f2 =9.9988 f2F = 217.6430 f2R = 13.5869 r2R = 4.8842 r3F = 9.0140 TL =37.9644 Σd = 22.5834 Ymax = 8.2000 (1) f/f1 = 0.0625 (2) f2/f1 = 0.0606(4) (r3F + r2R)/(r3F − r2R) = 3.3653 (5) TL/Σd = 1.6811 (6) TL/Ymax =4.6298 (7) f2R/|f2F| = 0.0624 (8) f/f2R = 0.7581

FIGS. 16A, 16B and 16C are graphs showing various aberrations of theimaging lens according to Example 8 of the second embodiment, in whichFIG. 16A is upon focusing on an infinity object, FIG. 16B is uponfocusing on a close shooting distance, and FIG. 16C is coma uponfocusing on an infinity object upon moving the shift lens groupvertically upward in FIG. 15 by an amount of 0.1 mm.

As is apparent from various graphs, the imaging lens according toExample 8 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object with minimally suppressing deterioration inoptical performance upon vibration reduction.

Example 9

FIG. 17 is a sectional view showing a lens configuration of an imaginglens according to Example 9 of the second embodiment of the presentapplication.

As shown in FIG. 17, the imaging lens according to Example 9 is composedof, in order from an unillustrated object side, a first lens group G1having positive refractive power, a second lens group G2 having positiverefractive power disposed with a distance from the first lens group G1,and a filter group FL disposed with a distance from the second lensgroup G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a front lens group G2F having positive refractive power, a first flarestopper FS1, an aperture stop S, a second flare stopper FS2, and a rearlens group G2R having positive refractive power.

The front lens group G2F is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, and a positive meniscus lens L22 having a convex surface facingthe object side.

The rear lens group G2R is composed of, in order from the object side, acemented lens constructed by a double concave negative lens L23 cementedwith a double convex positive lens L24, and a double convex positivelens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 9, focusing from an infinityobject to a close object is carried out by moving the rear lens groupG2R, which is a portion of the second lens group G2, along the opticalaxis toward the object side. Incidentally, the position of the firstlens group G1 is fixed with respect to the image plane I.

Moreover, in the imaging lens according to Example 9, the whole of thesecond lens group is moved as a shift lens group in a directionincluding a component perpendicular to the optical axis, therebycorrecting an image blur upon generating a camera shake.

Various values associated with the imaging lens according to Example 9are listed in Table 9.

TABLE 9 (Specifications) f = 10.30 FNO = 2.92 2ω = 78.60 Y = 8.20 TL =37.97 BF = 15.46 ACTL = 37.02 ACBF = 14.51 (Lens Data) i r d nd νd 1346.0582 1.20 1.60300 65.44 2 −346.0893 d2 3 24.3607 1.20 1.58313 59.38*4 4.6967 3.70 5 9.3473 2.90 1.74950 35.28 6 305.1987 0.30 7 ∞ 1.70Flare Stopper FS1 8 ∞ 1.40 Aperture Stop S 9 ∞ d9 Flare Stopper FS2 10−9.2201 1.00 1.80810 22.76 11 77.4450 2.70 1.75500 52.32 12 −10.98300.40 13 25.7154 2.95 1.59201 67.02 *14 −12.9856 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.6967 κ= +0.1147 C4 = +5.5141E−4 C6 = +3.4495E−6 C8 = +3.3752E−7 C10 =−9.7228E−10 Surface Number = 14 r = −12.9856 κ = −10.9391 C4 =−4.1228E−4 C6 = +1.5051E−5 C8 = −2.5702E−7 C10 = +2.1453E−9 (VariableDistances) INF CLD d2 = 2.1557 2.1557 d9 = 0.9000 0.6716 d14 = 10.563710.7921 d20 = 0.7000 0.7000 (Lens Group Data) Group I Focal Length 1 1287.1468 2 3 10.1322 (Values for Conditional Expressions) f = 10.3000 f1= 287.1468 f2 = 10.1322 f2F = 152.2949 f2R = 13.7383 r2R = 4.6967 r3F =9.3473 TL = 37.9694 Σd = 22.5057 Ymax = 8.2000 (1) f/f1 = 0.0359 (2)f2/f1 = 0.0353 (4) (r3F + r2R)/(r3F − r2R) = 3.0199 (5) TL/Σd = 1.6871(6) TL/Ymax = 4.6304 (7) f2R/|f2F| = 0.0902 (8) f/f2R = 0.7497

FIGS. 18A, 18B and 18C are graphs showing various aberrations of theimaging lens according to Example 9 of the second embodiment, in whichFIG. 18A is upon focusing on an infinity object, FIG. 18B is uponfocusing on a close shooting distance, and FIG. 18C is coma uponfocusing on an infinity object upon moving the shift lens groupvertically upward in FIG. 17 by an amount of 0.1 mm.

As is apparent from various graphs, the imaging lens according toExample 9 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object with minimally suppressing deterioration inoptical performance upon vibration reduction.

Example 10

FIG. 19 is a sectional view showing a lens configuration of an imaginglens according to Example 10 of the second embodiment of the presentapplication.

As shown in FIG. 19, the imaging lens according to Example 10 iscomposed of, in order from an unillustrated object side, a first lensgroup G1 having positive refractive power, a second lens group G2 havingpositive refractive power disposed with a distance from the first lensgroup G1, and a filter group FL disposed with a distance from the secondlens group G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a front lens group G2F having positive refractive power, a first flarestopper FS1, an aperture stop S, a second flare stopper FS2, and a rearlens group G2R having positive refractive power.

The front lens group G2F is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, and a positive meniscus lens L22 having a convex surface facingthe object side.

The rear lens group G2R is composed of, in order from the object side, acemented lens constructed by a double concave negative lens L23 cementedwith a double convex positive lens L24, and a double convex positivelens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 10, focusing from an infinityobject to a close object is carried out by moving the whole of thesecond lens group G2 along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Moreover, in the imaging lens according to Example 10, the rear lensgroup G2R of the second lens group is moved as a shift lens group in adirection including a component perpendicular to the optical axis,thereby correcting an image blur upon generating a camera shake.

Various values associated with the imaging lens according to Example 10are listed in Table 10.

TABLE 10 (Specifications) f = 10.30 FNO = 2.91 2ω = 78.62 Y = 8.20 TL =37.57 BF = 15.47 ACTL = 36.62 ACBF = 14.52 (Lens Data) i r d nd νd 1332.7704 1.00 1.60300 65.44 2 −332.7936 d2 3 22.0308 1.10 1.58313 59.38*4 4.5012 3.45 5 9.0325 3.05 1.74950 35.28 6 117.5529 0.30 7 ∞ 1.70Flare Stopper FS1 8 ∞ 1.60 Aperture Stop S 9 ∞ 0.70 Flare Stopper FS2 10−10.0955 1.00 1.80810 22.76 11 52.5077 2.70 1.75500 52.32 12 −11.59740.40 13 24.8237 2.97 1.59201 67.05 *14 −12.8447 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.5012 κ= +0.3479 C4 = +3.0704E−4 C6 = +9.9005E−7 C8 = +3.7811E−7 C10 =−1.2499E−9 Surface Number = 14 r = −12.8447 κ = −10.3357 C4 = −4.0200E−4C6 = +1.4415E−5 C8 = −2.4522E−7 C10 = +2.0151E−9 (Variable Distances)INF CLD d2 = 2.1344 1.9074 d14 = 10.6000 10.8270 d20 = 0.6652 0.6652(Lens Group Data) Group I Focal Length 1 1 276.0942 2 3 10.1310 (Valuesfor Conditional Expressions) f = 10.2975 f1 = 276.0942 f2 = 10.1310 f2F= 824.1941 f2R = 13.3447 r2R = 4.5012 r3F = 9.0325 TL = 37.5652 Σd =22.1000 Ymax = 8.2000 (1) f/f1 = 0.0373 (2) f2/f1 = 0.0367 (4) (r3F +r2R)/(r3F − r2R) = 2.9867 (5) TL/Σd = 1.6998 (6) TL/Ymax = 4.5811 (7)f2R/|f2F| = 0.0162 (8) f/f2R = 0.7717

FIGS. 20A, 20B and 20C are graphs showing various aberrations of theimaging lens according to Example 10 of the second embodiment, in whichFIG. 20A is upon focusing on an infinity object, FIG. 20B is uponfocusing on a close shooting distance, and FIG. 20C is coma uponfocusing on an infinity object upon moving the shift lens groupvertically upward in FIG. 19 by an amount of 0.1 mm.

As is apparent from various graphs, the imaging lens according toExample 10 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object with minimally suppressing deterioration inoptical performance upon vibration reduction.

Example 11

FIG. 21 is a sectional view showing a lens configuration of an imaginglens according to Example 11 of the second embodiment of the presentapplication.

As shown in FIG. 21, the imaging lens according to Example 11 iscomposed of, in order from an unillustrated object side, a first lensgroup G1 having positive refractive power, a second lens group G2 havingpositive refractive power disposed with a distance from the first lensgroup G1, and a filter group FL disposed with a distance from the secondlens group G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a front lens group G2F having positive refractive power, a first flarestopper FS1, an aperture stop S, a second flare stopper FS2, and a rearlens group G2R having positive refractive power.

The front lens group G2F is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, and a positive meniscus lens L22 having a convex surface facingthe object side.

The rear lens group G2R is composed of, in order from the object side, acemented lens constructed by a double concave negative lens L23 cementedwith a double convex positive lens L24, and a double convex positivelens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 11, focusing from an infinityobject to a close object is carried out by moving the whole of thesecond lens group G2 along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Moreover, in the imaging lens according to Example 11, the rear lensgroup G2R of the second lens group is moved as a shift lens group in adirection including a component perpendicular to the optical axis,thereby correcting an image blur upon generating a camera shake.

Various values associated with the imaging lens according to Example 11are listed in Table 11.

TABLE 11 (Specifications) f = 10.30 FNO = 2.89 2ω = 78.61 Y = 8.20 TL =37.47 BF = 15.38 ACTL = 36.52 ACBF = 14.43 (Lens Data) i r d nd νd 1290.4936 1.00 1.51680 64.11 2 −290.7707 d2 3 19.6032 1.10 1.58913 61.15*4 4.4561 3.25 5 9.1671 3.75 1.74950 35.28 6 79.1129 0.30 7 ∞ 1.70 FlareStopper FS1 8 ∞ 1.05 Aperture Stop S 9 ∞ 1.25 Flare Stopper FS2 10−11.3274 1.15 1.80810 22.76 11 44.4829 2.75 1.75500 52.32 12 −11.52210.50 13 23.9759 3.00 1.59201 67.02 *14 −14.2191 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.4561 κ= +0.6048 C4 = −2.4225E−5 C6 = −1.1037E−5 C8 = +5.0943E−7 C10 =−1.8920E−8 Surface Number = 14 r = −14.2191 κ = −11.3728 C4 = −3.1719E−4C6 = +1.0532E−5 C8 = −1.6628E−7 C10 = +1.2559E−9 (Variable Distances)INF CLD d2 = 1.2865 1.0592 d14 = 10.5135 10.7408 d20 = 0.6702 0.6702(Lens Group Data) Group I Focal Length 1 1 281.3493 2 3 10.1574 (Valuesfor Conditional Expressions) f = 10.3000 f1 = 281.3493 f2 = 10.1574 f2F= −195.0408 f2R = 12.8820 r2R = 4.4561 r3F = 9.1671 TL = 37.4702 Σd =22.0865 Ymax = 8.2000 (1) f/f1 = 0.0366 (2) f2/f1 = 0.0361 (4) (r3F +r2R)/(r3F − r2R) = 2.8917 (5) TL/Σd = 1.6965 (6) TL/Ymax = 4.5695 (7)f2R/|f2F| = 0.0660 (8) f/f2R = 0.7996

FIGS. 22A, 22B and 22C are graphs showing various aberrations of theimaging lens according to Example 11 of the second embodiment, in whichFIG. 22A is upon focusing on an infinity object, FIG. 22B is uponfocusing on a close shooting distance, and FIG. 22C is coma uponfocusing on an infinity object upon moving the shift lens groupvertically upward in FIG. 21 by an amount of 0.1 mm.

As is apparent from various graphs, the imaging lens according toExample 11 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object with minimally suppressing deterioration inoptical performance upon vibration reduction.

Example 12

FIG. 23 is a sectional view showing a lens configuration of an imaginglens according to Example 12 of the second embodiment of the presentapplication.

As shown in FIG. 23, the imaging lens according to Example 12 iscomposed of, in order from an unillustrated object side, a first lensgroup G1 having positive refractive power, a second lens group G2 havingpositive refractive power disposed with a distance from the first lensgroup G1, and a filter group FL disposed with a distance from the secondlens group G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a front lens group G2F having positive refractive power, a first flarestopper FS1, an aperture stop S, a second flare stopper FS2, and a rearlens group G2R having positive refractive power.

The front lens group G2F is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, and a positive meniscus lens L22 having a convex surface facingthe object side.

The rear lens group G2R is composed of, in order from the object side, acemented lens constructed by a double concave negative lens L23 cementedwith a double convex positive lens L24, and a double convex positivelens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 12, focusing from an infinityobject to a close object is carried out by moving the rear lens groupG2R, which is a portion of the second lens group G2, along the opticalaxis toward the object side. Incidentally, the position of the firstlens group G1 is fixed with respect to the image plane I.

Moreover, in the imaging lens according to Example 12, the rear lensgroup G2R of the second lens group G2 is moved as a shift lens group ina direction including a component perpendicular to the optical axis,thereby correcting an image blur upon generating a camera shake.

Various values associated with the imaging lens according to Example 12are listed in Table 12.

TABLE 12 (Specifications) f = 10.30 FNO = 2.92 2ω = 78.60 Y = 8.20 TL =37.45 BF = 15.52 ACTL = 36.50 ACBF = 14.57 (Lens Data) i r d nd νd 1367.5465 1.00 1.60300 65.44 2 −368.4597 d2 3 21.2966 1.10 1.58313 59.38*4 4.4652 3.35 5 9.2118 3.50 1.74950 35.28 6 129.9098 0.30 7 ∞ 1.70Flare Stopper FS1 8 ∞ 1.60 Aperture Stop S 9 ∞ d9 Flare Stopper FS2 10−10.7870 1.10 1.80810 22.76 11 46.2743 2.75 1.75500 52.32 12 −11.64410.40 13 25.7948 2.95 1.59201 67.02 *14 −13.3762 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.4652 κ= +0.3656 C4 = +2.6809E−4 C6 = +1.6171E−6 C8 = +2.8446E−7 C10 =+2.2563E−10 Surface Number = 14 r = −13.3762 κ = −11.1665 C4 =−3.9072E−4 C6 = +1.3411E−5 C8 = −2.2460E−7 C10 = +1.8090E−9 (VariableDistances) INF CLD d2 = 1.4850 1.4850 d9 = 0.7000 0.4728 d14 = 10.648910.8762 d20 = 0.6663 0.6663 (Lens Group Data) Group I Focal Length 1 1305.2986 2 3 10.1676 (Values for Conditional Expressions) f = 10.3000 f1= 305.2986 f2 = 10.1676 f2F = −1011.0523 f2R = 13.2321 r2R = 4.4652 r3F= 9.2118 TL = 37.4502 Σd = 21.9350 Ymax = 8.2000 (1) f/f1 = 0.0337 (2)f2/f1 = 0.0333 (4) (r3F + r2R)/(r3F − r2R) = 2.8814 (5) TL/Σd = 1.7073(6) TL/Ymax = 4.5671 (7) f2R/|f2F| = 0.0131 (8) f/f2R = 0.7784

FIGS. 24A, 24B and 24C are graphs showing various aberrations of theimaging lens according to Example 12 of the second embodiment, in whichFIG. 24A is upon focusing on an infinity object, FIG. 24B is uponfocusing on a close shooting distance, and FIG. 24C is coma uponfocusing on an infinity object upon moving the shift lens groupvertically upward in FIG. 23 by an amount of 0.1 mm.

As is apparent from various graphs, the imaging lens according toExample 12 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object with minimally suppressing deterioration inoptical performance upon vibration reduction.

Example 13

FIG. 25 is a sectional view showing a lens configuration of an imaginglens according to Example 13 of the second embodiment of the presentapplication.

As shown in FIG. 25, the imaging lens according to Example 11 iscomposed of, in order from an unillustrated object side, a first lensgroup G1 having positive refractive power, a second lens group G2 havingpositive refractive power disposed with a distance from the first lensgroup G1, and a filter group FL disposed with a distance from the secondlens group G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a front lens group G2F having positive refractive power, a first flarestopper FS1, an aperture stop S, a second flare stopper FS2, and rearlens group G2R having positive refractive power.

The front lens group G2F is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, and a positive meniscus lens L22 having a convex surface facingthe object side.

The rear lens group G2R is composed of, in order from the object side, acemented lens constructed by a double concave negative lens L23 cementedwith a double convex positive lens L24, and a double convex positivelens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 13, focusing from an infinityobject to a close object is carried out by moving the whole of thesecond lens group G2 along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Moreover, in the imaging lens according to Example 13, the rear lensgroup G2R of the second lens group is moved as a shift lens group in adirection including a component perpendicular to the optical axis,thereby correcting an image blur upon generating a camera shake.

Various values associated with the imaging lens according to Example 13are listed in Table 13.

TABLE 13 (Specifications) f = 10.30 FNO = 2.91 2ω = 78.61 Y = 8.20 TL =37.79 BF = 15.45 ACTL = 36.84 ACBF = 14.50 (Lens Data) i r d nd νd 1160.4134 1.52 1.51633 64.14 2 −160.4538 d2 3 23.9005 1.10 1.58313 59.38*4 4.4680 3.19 5 8.8845 3.00 1.74950 35.28 6 59.7352 0.30 7 ∞ 1.70 FlareStopper FS1 8 ∞ 1.05 Aperture Stop S 9 ∞ 1.25 Flare Stopper FS2 10−10.3948 1.00 1.80810 22.76 11 53.0153 2.70 1.75500 52.32 12 −10.81130.40 13 22.9281 2.99 1.59201 67.05 *14 −14.0952 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.4680 κ= +0.4037 C4 = +2.7434E−4 C6 = +4.0423E−6 C8 = +1.7001E−7 C10 =+1.0858E−8 Surface Number = 14 r = −14.0952 κ = −11.0203 C4 = −3.0335E−4C6 = +1.0309E−5 C8 = −1.5359E−7 C10 = +1.0836E−9 (Variable Distances)INF CLD d2 = 2.1336 1.9062 d14 = 10.5627 10.7901 d20 = 0.6862 0.6862(Lens Group Data) Group I Focal Length 1 1 155.6106 2 3 9.9966 (Valuesfor Conditional Expressions) f = 10.3014 f1 = 155.6106 f2 = 9.9966 f2F =−107.3070 f2R = 12.6842 r2R = 4.4680 r3F = 8.8845 TL = 37.7862 Σd =22.3373 Ymax = 8.2000 (1) f/f1 = 0.0662 (2) f2/f1 = 0.0642 (4) (r3F +r2R)/(r3F − r2R) = 3.0233 (5) TL/Σd = 1.6916 (6) TL/Ymax = 4.6081 (7)f2R/|f2F| = 0.1182 (8) f/f2R = 0.8121

FIGS. 26A, 26B and 26C are graphs showing various aberrations of theimaging lens according to Example 13 of the second embodiment, in whichFIG. 26A is upon focusing on an infinity object, FIG. 26B is uponfocusing on a close shooting distance, and FIG. 26C is coma uponfocusing on an infinity object upon moving the shift lens groupvertically upward in FIG. 25 by an amount of 0.1 mm.

As is apparent from various graphs, the imaging lens according toExample 13 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object with minimally suppressing deterioration inoptical performance upon vibration reduction.

Example 14

FIG. 27 is a sectional view showing a lens configuration of an imaginglens according to Example 14 of the second embodiment of the presentapplication.

As shown in FIG. 27, the imaging lens according to Example 14 iscomposed of, in order from an unillustrated object side, a first lensgroup G1 having positive refractive power, a second lens group G2 havingpositive refractive power disposed with a distance from the first lensgroup G1, and a filter group FL disposed with a distance from the secondlens group G2.

The first lens group G1 is composed of a double convex positive lens L11only.

The second lens group G2 is composed of, in order from the object side,a front lens group G2F having positive refractive power, a first flarestopper FS1, an aperture stop S, a second flare stopper FS2, and a rearlens group G2R having positive refractive power.

The front lens group G2F is composed of, in order from the object side,a negative meniscus lens L21 having a convex surface facing the objectside, and a positive meniscus lens L22 having a convex surface facingthe object side.

The rear lens group G2R is composed of, in order from the object side, acemented lens constructed by a double concave negative lens L23 cementedwith a double convex positive lens L24, and a double convex positivelens L25.

The filter group FL is composed of a low-pass filter, aninfrared-light-blocking filter, and the like.

In the imaging lens according to Example 14, focusing from an infinityobject to a close object is carried out by moving the whole of thesecond lens group G2 along the optical axis toward the object side.Incidentally, the position of the first lens group G1 is fixed withrespect to the image plane I.

Moreover, in the imaging lens according to Example 14, the whole of thesecond lens group is moved as a shift lens group in a directionincluding a component perpendicular to the optical axis, therebycorrecting an image blur upon generating a camera shake.

Various values associated with the imaging lens according to Example 14are listed in Table 14.

TABLE 14 (Specifications) f = 10.30 FNO = 2.94 2ω = 78.61 Y = 8.20 TL =37.86 BF = 15.56 ACTL = 36.91 ACBF = 14.61 (Lens Data) i r d nd νd 1307.5313 1.20 1.48749 70.23 2 −307.5947 d2 3 21.9567 1.10 1.58313 59.38*4 4.5581 3.45 5 9.6306 3.05 1.74950 35.28 6 292.4663 0.30 7 ∞ 1.70Flare Stopper FS1 8 ∞ 1.05 Aperture Stop S 9 ∞ 1.25 Flare Stopper FS2 10−8.9112 1.00 1.80810 22.76 11 506.5428 2.70 1.75500 52.32 12 −9.37930.40 13 21.0314 2.97 1.49700 81.61 *14 −13.3938 d14 15 ∞ 0.50 1.5163364.14 16 ∞ 1.11 17 ∞ 1.59 1.51633 64.14 18 ∞ 0.30 19 ∞ 0.70 1.5163364.14 20 ∞ d20 (Aspherical Surface Data) Surface Number = 4 r = 4.5581 κ= +0.1979 C4 = +4.8517E−4 C6 = +5.1785E−6 C8 = +2.7432E−7 C10 =+2.0130E−9 Surface Number = 14 r = −13.3938 κ = −12.8217 C4 = −4.2055E−4C6 = +1.6915E−5 C8 = −2.9730E−7 C10 = +2.4991E−9 (Variable Distances)INF CLD d2 = 2.1354 1.9083 d14 = 10.6990 10.9261 d20 = 0.6645 0.6645(Lens Group Data) Group I Focal Length 1 1 315.6575 2 3 10.1518 (Valuesfor Conditional Expressions) f = 10.3000 f1 = 315.6575 f2 = 10.1518 f2F= 1702.3764 f2R = 13.3866 r2R = 4.5581 r3F = 9.6306 TL = 37.8645 Σd =22.3010 Ymax = 8.2000 (1) f/f1 = 0.0326 (2) f2/f1 = 0.0322 (4) (r3F +r2R)/(r3F − r2R) = 2.7972 (5) TL/Σd = 1.6979 (6) TL/Ymax = 4.6176 (7)f2R/|f2F| = 0.0079 (8) f/f2R = 0.7694

FIGS. 28A, 28B and 28C are graphs showing various aberrations of theimaging lens according to Example 14 of the second embodiment, in whichFIG. 28A is upon focusing on an infinity object, FIG. 28B is uponfocusing on a close shooting distance, and FIG. 28C is coma uponfocusing on an infinity object upon moving the shift lens groupvertically upward in FIG. 27 by an amount of 0.1 mm.

As is apparent from various graphs, the imaging lens according toExample 13 shows superb optical performance as a result of goodcorrections to various aberrations over entire focusing range frominfinity to a close object with minimally suppressing deterioration inoptical performance upon vibration reduction.

Each example described above makes it possible to provide a compactimaging lens having a wide angle of view of 60 degrees or more, a largeaperture of an f-number of about 2.8 and excellent optical performanceover entire image frame with excellently correcting various aberrationsupon focusing on an infinity object to a close object, and minimallysuppressing deterioration in optical performance upon vibrationreduction.

In an imaging lens according to each Example, a back focal length, whichis a distance along the optical axis between the image side lens surfaceof a lens disposed to the most image side and the image plane, ispreferably from about 10.0 mm to 30.0 mm in the smallest state.Moreover, in an imaging lens according to each Example, the image heightis preferably 5.0 mm to 12.5 mm, and most preferably 5.0 mm to 9.5 mm.

Then, an outline of a method for manufacturing an imaging lens accordingto the second embodiment is explained below with reference to FIG. 33.

FIG. 33 is a flowchart showing a method for manufacturing an imaginglens according to the second embodiment of the present application.

The method for manufacturing an imaging lens according to the secondembodiment of the present application is a method for manufacturing animaging lens including, in order from an object side, a first lens grouphaving positive refractive power and a second lens group having positiverefractive, the method includes the following steps S21 through S23:

Step S21: disposing the first lens group with a single lens component;

Step S22: disposing the second lens group consisting of, in order fromthe object side, a front lens group, an aperture stop, and a rear lensgroup into a lens barrel in order from the object side; and

Step S23: moving the second lens group or the rear lens group as a shiftlens group in a direction including a component perpendicular to theoptical axis by providing a well-known moving mechanism in the lensbarrel.

With this method for manufacturing an imaging lens according to thesecond embodiment of the present application, it becomes possible tomanufacture a compact imaging lens having a wide angle of view, a largeaperture and excellent optical performance over entire image frame withexcellently correcting various aberrations upon focusing on an infinityobject to a close object.

The present embodiment only shows a specific example for the purpose ofbetter understanding of the present application. Accordingly, it isneedless to say that the present application in its broader aspect isnot limited to the specific details and representative devices.Incidentally, the following description may suitably be applied withinlimits that do not deteriorate optical performance.

As numerical examples of an imaging lens according to the presentapplication, although a two-lens-group configuration is shown, thelens-group configuration according to the present application is notlimited to this, other lens-group configurations such as athree-lens-group configuration is possible to configure an imaging lens.Specifically, a lens configuration that a lens or a lens group is addedto the most object side or the most image side of an imaging lensaccording to the present application is possible. Incidentally, a lensgroup means a portion that includes at least one lens and is separatedby air spaces.

In an imaging lens according to the present application, in order tovary focusing from infinity to a close object, a portion of a lensgroup, a single lens group, or a plurality of lens groups may be movedalong the optical axis as a focusing lens group. Focusing may be carriedout by other configuration than the above-described Examples such as anobject side portion of the second lens group (the negative meniscus lensL21 and the positive meniscus lens L22), or each single lens componentof the whole lens system.

In this case, the focusing lens group can be used for auto focus, andsuitable for being driven by a motor such as an ultrasonic motor. It isparticularly preferable that a portion or the whole of the second lensgroup G2 is moved as the focusing lens group.

A lens group or a portion of a lens group may be shifted in a directionincluding a component perpendicular to the optical axis as a vibrationreduction lens group, or tilted (swayed) in a direction including theoptical axis for correcting an image blur caused by a camera shake, inother words, vibration correction. It is particularly preferable that aportion or the whole of the second lens group is used as a shift lensgroup.

A lens surface of a lens may be a spherical surface, a plane surface, oran aspherical surface. When a lens surface is a spherical surface or aplane surface, lens processing, assembling and adjustment become easy,and deterioration in optical performance caused by lens processing,assembling and adjustment errors can be prevented, so that it ispreferable. Moreover, even if the image plane is shifted, deteriorationin optical performance is little, so that it is preferable. When a lenssurface is an aspherical surface, the aspherical surface may befabricated by a fine grinding process, a glass molding process that aglass material is formed into an aspherical shape by a mold, or acompound type process that a resin material is formed into an asphericalshape on a glass lens surface. A lens surface may be a diffractiveoptical surface, and a lens may be a graded-index type lens (GRIN lens)or a plastic lens.

Although an aperture stop S is preferably provided in or in the vicinityof the second lens group, the function may be substituted by a lensframe without disposing a member as an aperture stop. Moreover, this isthe same to the first and the second flare stoppers provided in animaging lens according to each Example of the present application.

An antireflection coating having high transmittance over a broadwavelength range may be applied to each lens surface of an imaging lensaccording to the present application to reduce flare or ghost images, sothat high optical performance with high contrast can be achieved.

In an imaging lens according to the present application, the first lensgroup preferably includes one positive lens component. The second lensgroup preferably includes three positive lens components and onenegative lens component, and, in particular, these lens components arepreferably disposed, in order from the object side,positive-positive-positive-negative with air spaces in between.Alternatively, the second lens group preferably includes two positivelens components and two negative lens components, and these lenscomponents are preferably disposed, in order from the object side,positive-negative-positive-negative with air spaces in between.

Then, a camera equipped with an imaging lens according to the presentapplication is explained with reference to FIGS. 29A, 29B and 30.

FIGS. 29A and 29B are diagrams showing an electronic camera according tothe present application, in which FIG. 29A is a front view and FIG. 29Bis a rear view. FIG. 30 is a sectional view along A-A′ line in FIG. 29A.

The camera 1 is an electronic still camera equipped with the imaginglens according to Example 1 as an image-taking lens 2 as shown in FIGS.29A through 30.

In the camera 1, when a power switch button (not shown) is pressed by aphotographer, a shutter (not shown) of an image-taking lens, whichblocks light from transmitting the image-taking lens 2, is opened.Accordingly, light from an object (not shown) is incident on theimage-taking lens 2, and converged on an imaging device C (for example,a CCD or CMOS) disposed on an image plane I by the image-taking lens 2,thereby forming an image of the object. The object image formed on theimaging device C is displayed on a liquid crystal monitor 3 disposedbackside of the camera 1. After fixing the image composition of theobject image with observing the liquid crystal monitor 3, a photographerdepresses a release button 4 to take a picture of the object image bythe imaging device C, and stores in a memory (not shown). In thismanner, the photographer can take a picture of the object by the camera1. In the camera 1, the following members are disposed such as anauxiliary light emitter 5 that emits auxiliary light when the object isdark, and a function button 7 that is used for setting variousconditions of the camera 1.

With this configuration, the camera 1 equipped with the imaging lensaccording to Example 1 as an image-taking lens 2 makes it possible torealize a compact optical apparatus having a wide angle of view, a largeaperture and excellent optical performance over entire image frame withexcellently correcting various aberrations upon focusing on an infinityobject to a close object. Incidentally, the same effect as the camera 1can be obtained by constructing a camera equipped with any one of theimaging lenses according to Example 2 through 7 as an image-taking lens2. Moreover, an imaging lens according to the present application is notlimited to the electronic still camera, and can be adopted to any otheroptical apparatus such as a digital video camera, and a film camera.Moreover, it may be adopted to an interchangeable lens.

1. An imaging lens comprising, in order from an object side: a firstlens group having positive refractive power; and a second lens grouphaving positive refractive power, a position of the first lens groupbeing fixed with respect to an image plane, the second lens groupconsisting of a plurality of lens components, and the followingconditional expression being satisfied:0.015<f/f1<0.085  where f denotes a focal length of the imaging lens,and f1 denotes a focal length of the first lens group.
 2. The imaginglens according to claim 1, wherein the first lens group consists of asingle positive lens component having a convex surface facing the objectside.
 3. The imaging lens according to claim 2, wherein the singlepositive lens component is a single lens.
 4. The imaging lens accordingto claim 1, wherein at least a portion of the second lens group is movedtoward the object side, thereby carrying out focusing from an infinityobject to a close object.
 5. The imaging lens according to claim 1,wherein the following conditional expression is satisfied:0.015<f2/f1<0.085 where f1 denotes a focal length of the first lensgroup, and f2 denotes a focal length of the second lens group.
 6. Theimaging lens according to claim 1, wherein the second lens groupincludes at least one aspherical surface.
 7. The imaging lens accordingto claim 1, wherein the following conditional expression is satisfied:0.80<f/f2<1.10 where f denotes a focal length of the imaging lens, andf2 denotes a focal length of the second lens group.
 8. The imaging lensaccording to claim 1, wherein the second lens group included, in orderfrom the object side, a negative meniscus lens having a convex surfacefacing the object side, a positive meniscus lens having a convex surfacefacing the object side, an aperture stop, a cemented lens constructed bya negative lens having a concave surface facing the object side cementedwith a positive lens having a convex surface facing the image side, anda positive lens.
 9. The imaging lens according to claim 1, wherein thefollowing conditional expression is satisfied:2.50<(r3F+r2R)/(r3F−r2R)<3.80 where r2R denotes a radius of curvature ofthe image side surface of the most object side lens component in thesecond lens group, and r3F denotes a radius of curvature of a lenssurface adjacent to the image side of the image side surface.
 10. Theimaging lens according to claim 1, wherein the most object side lenscomponent of the second lens group includes at least one asphericalsurface.
 11. The imaging lens according to claim 1, wherein theplurality of lens components in the second lens group includes at leastone positive lens component, and the most image side positive lenscomponent in the at least one positive lens component includes at leastone aspherical surface.
 12. The imaging lens according to claim 1,wherein the following conditional expression is satisfied:1.55<TL/Σd<1.75 where TL denotes a total lens length of the imaginglens, and Σd denotes a distance along an optical axis between the mostobject side lens surface in the first lens group and the most image sidelens surface in the second lens group.
 13. The imaging lens according toclaim 1, wherein the following conditional expression is satisfied:4.00<TL/Ymax<5.00 where TL denotes a total lens length of the imaginglens, and Ymax denotes the maximum image height of the imaging lens. 14.The imaging lens according to claim 1, wherein an aperture stop isdisposed in the second lens group.
 15. An optical apparatus equippedwith the imaging lens according to claim
 1. 16. An imaging lenscomprising, in order from an object side: a first lens group havingpositive refractive power; and a second lens group having positiverefractive power, the first lens group consisting of a single lenscomponent, the second lens group consisting of, in order from the objectside, a front lens group, an aperture stop, and a rear lens group, andat least a portion of the second lens group being moved as a shift lensgroup in a direction including a component perpendicular to an opticalaxis.
 17. The imaging lens according to claim 16, wherein the followingconditional expression is satisfied:0.00<f2R/|f2F|<0.20 where f2F denotes a focal length of the front lensgroup, and f2R denotes a focal length of the rear lens group.
 18. Theimaging lens according to claim 16, wherein the rear lens groupincludes, in order from an object side, a cemented lens constructed by anegative lens having a concave surface facing the object cemented with apositive lens having a convex surface facing the image side, and adouble convex positive lens.
 19. The imaging lens according to claim 16,wherein at least a portion of the second lens group is moved along anoptical axis, thereby carrying out focusing from an infinity object to aclose object.
 20. The imaging lens according to claim 16, wherein thefront lens group includes, in order from the object side, a negativemeniscus lens having a convex surface facing the object side.
 21. Theimaging lens according to claim 16, wherein the front lens groupincludes a plurality of lens components, and the following conditionalexpression is satisfied:2.50<(r3F+r2R)/(r3F−r2R)<3.80 where r2R denotes a radius of curvature ofthe image side surface of the most object side lens component in thesecond lens group, and r3F denotes a radius of curvature of a lenssurface adjacent to the image side of the image side surface.
 22. Theimaging lens according to claim 16, wherein the following conditionalexpression is satisfied:1.55<TL/Σd<1.75 where TL denotes a total lens length of the imaginglens, and Σd denotes a distance along an optical axis between the mostobject side lens surface in the first lens group and the most image sidelens surface in the second lens group.
 23. The imaging lens according toclaim 16, wherein the following conditional expression is satisfied:4.00<TL/Ymax<5.00 where TL denotes a total lens length of the imaginglens, and Ymax denotes the maximum image height of the imaging lens. 24.The imaging lens according to claim 16, wherein the followingconditional expression is satisfied:0.015<f2/f1<0.085 where f1 denotes a focal length of the first lensgroup, and f2 denotes a focal length of the second lens group.
 25. Theimaging lens according to claim 16, wherein the following conditionalexpression is satisfied:0.70<f/f2R<0.85 where f denotes a focal length of the imaging lens, andf2R denotes a focal length of the rear lens group.
 26. The imaging lensaccording to claim 16, wherein the first lens group consists of apositive lens having a convex surface facing the object side.
 27. Theimaging lens according to claim 16, wherein a position of the first lensgroup is fixed with respect to the image plane.
 28. The imaging lensaccording to claim 16, wherein the following conditional expression issatisfied:0.015<f/f1<0.085 where f denotes a focal length of the imaging lens, andf1 denotes a focal length of the first lens group.
 29. The imaging lensaccording to claim 16, wherein the front lens group includes at leastone aspherical surface.
 30. The imaging lens according to claim 16,wherein the front lens group includes a plurality of lens components,and the most object side lens component in the front lens includes atleast one aspherical surface.
 31. The imaging lens according to claim16, wherein the rear lens group includes at least one asphericalsurface.
 32. The imaging lens according to claim 16, wherein the rearlens group includes a plurality of lens components, and the most imageside lens component in the rear lens group includes at least oneaspherical surface.
 33. An optical apparatus equipped with the imaginglens according to claim
 16. 34. An imaging lens comprising, in orderfrom an object side: a first lens group having positive refractivepower; and a second lens group having positive refractive power, thefirst lens group consisting of a single positive lens component havingconvex surface facing an image side, the second lens group consistingof, in order from the object side, a negative meniscus lens having aconvex surface facing the object side, a positive lens having a convexsurface facing the object side, an aperture stop, a cemented lensconstructed by a negative lens having a concave surface facing theobject side cemented with a positive lens having a convex surface facingthe image side, and a positive lens, and at least a portion of thesecond lens group being moved along an optical axis, thereby carryingout focusing from an infinity object to a close object.
 35. An opticalapparatus equipped with the imaging lens according to claim
 34. 36. Amethod for manufacturing an imaging lens including, in order from anobject side, a first lens group having positive refractive power and asecond lens group having positive refractive power, the methodcomprising steps of: disposing the second lens group with consisting ofa plurality of lens components; disposing the imaging lens withsatisfying the following conditional expression:0.015<f/f1<0.085  where f denotes a focal length of the imaging lens,and f1 denotes a focal length of the first lens group; and fixing aposition of the first lens group with respect to the image plane. 37.The method according to claim 36, further comprising a step of:disposing the first lens group consisting of a single positive lenscomponent having a convex surface facing the object side.
 38. The methodaccording to claim 36, further comprising a step of: satisfying thefollowing conditional expression:0.015<f2/f1<0.085  where f1 denotes a focal length of the first lensgroup, and f2 denotes a focal length of the second lens group.
 39. Themethod according to claim 36, further comprising a step of: satisfyingthe following conditional expression:0.80<f/f2<1.10  where f denotes a focal length of the imaging lens, andf2 denotes a focal length of the second lens group.
 40. The methodaccording to claim 36, further comprising a step of: satisfying thefollowing conditional expression:2.50<(r3F+r2R)/(r3F−r2R)<3.80  where r2R denotes a radius of curvatureof the image side surface of the most object side lens component in thesecond lens group, and r3F denotes a radius of curvature of a lenssurface adjacent to the image side of the image side surface.
 41. Amethod for manufacturing an imaging lens including, in order from theobject side, a first lens group having positive refractive power and asecond lens group having positive refractive power, the methodcomprising steps of: disposing the first lens group with a single lenscomponent; disposing the second lens group consisting of, in order fromthe object side, a front lens group, an aperture stop, and a rear lensgroup; and moving at least a portion of the second lens group as a shiftlens group in a direction including a component perpendicular to anoptical axis.
 42. The method according to claim 41, further comprising astep of: satisfying the following conditional expression:0.00<f2R/|f2F|<0.20  where f2F denotes a focal length of the front lensgroup, and f2R denotes a focal length of the rear lens group.
 43. Themethod according to claim 41, further comprising a step of: satisfyingthe following conditional expression:2.50<(r3F+r2R)/(r3F−r2R)<3.80  where r2R denotes a radius of curvatureof the image side surface of the most object side lens component in thesecond lens group, and r3F denotes a radius of curvature of a lenssurface adjacent to the image side of the image side surface.
 44. Amethod for manufacturing an imaging lens including, in order from anobject side, a first lens group having positive refractive power and asecond lens group having positive refractive power, the methodcomprising steps of: disposing the first lens group with a singlepositive lens component having a convex surface facing an image side;disposing the second lens group consisting of, in order from the objectside, a negative meniscus lens having a convex surface facing the objectside, a positive lens having a convex surface facing the object side, anaperture stop, a cemented lens constructed by a negative lens having aconcave surface facing the object side cemented with a positive lenshaving a convex surface facing the image side, and a positive lens; andmoving at least a portion of the second lens group along an opticalaxis, thereby carrying out focusing from an infinity object to a closeobject.